Using OpenACC with GeForce 680

Accelerated Computing HPC Compilers Legacy PGI Compilers
1

Hi all,

I am trying to figure out if I can utilize OpenACC to speed up the calculations of my fortran code. The first question to begin with is, do I have to have a tesla card to run OpenACC? can I just use GeForce 680?

here is the code and what I get when I compile/run it:

nx = 962 ! vector size, matrix size.
nxm1 = 961
nym1 = 961
!$acc data copyin(aj,bj,cj,dj,ar,aw,p,ae,as,an,ap,xref,yref), copyout(aj,bj,cj,dj)
!$acc parallel loop, private(aj1,bj1,cj1,dj1,xmxp,ymyp)
		do i=2,nxm1
          im1=i-1
          ip1=i+1
          xmxp=(xref(ip1)-xref(im1))/2.d0
!
          aj(im1)=0.d0
          bj(im1)=0.d0
          cj(im1)=0.d0
          dj(im1)=0.d0
!
		  aj1=0.d0
          bj1=0.d0
          cj1=0.d0
          dj1=0.d0
          do j=2,nym1
            jm1=j-1
            jp1=j+1
            ymyp=(yref(jp1)-yref(jm1))/2.d0
!
            aj1=aj1+aw(im1,jm1)
            bj1=bj1+ap(im1,jm1)
            if(j.ne.2) bj1=bj1+as(im1,jm1)
            if(j.ne.nym1) bj1=bj1+an(im1,jm1)
            cj1=cj1+ae(im1,jm1)
            dj1=dj1+ar(im1,jm1)-aw(im1,jm1)*p(im1,j)    &
                    -ae(im1,jm1)*p(ip1,j)-as(im1,jm1)*p(i,jm1)  &
                    -an(im1,jm1)*p(i,jp1)-ap(im1,jm1)*p(i  ,j)
!
          enddo
          aj(im1)=aj1
          bj(im1)=bj1
          cj(im1)=cj1
          dj(im1)=dj1
        enddo
!$acc end parallel loop
!$acc end data

compiler options:
acc=autopar,required -Mcuda=cuda7.0 -fast -Minform=warn -Mprof=dwarf -Minfo=accel PGI_ACC_TIME=1

compiler o/p:

290, Generating copyout(aj(:),bj(:),cj(:),dj(:))
         Generating copyin(ar(:,:),aw(:,:),p(:,:),ae(:,:),as(:,:),an(:,:),ap(:,:),xref(:),yref(:))
291, Accelerator kernel generated
        Generating Tesla code
291, Sum reduction generated for aj1,bj1,cj1,dj1
292, !$acc loop gang, vector(128) ! blockidx%x threadidx%x
306, Loop carried scalar dependence for bj1 at line 312
         Scalar last value needed after loop for bj1 at line 322
========== Rebuild All: 1 succeeded, 0 failed, 0 skipped ==========

I am using windows 8.1, visual studio 2010, pgi visual fortran 15.7.

when I run and check the execution time for both cpu and gpu, they are the same. Even when I increase the matrices size to 962x962 elements. vectors size is 962.

am I doing something wrong here? why don’t I have faster execution time with GPU? why can’t I see pgi profiler output upon running the code?

There is an error between aj generated in gpu compared to cpu version. the error is 3.3e-4. why is the error is relatively large?

Please advice
Dolf

2

Hi Dolf,

Let’s try the following schedule:

nx = 962 ! vector size, matrix size. 
nxm1 = 961 
nym1 = 961 
!$acc data copyin(ar,aw,p,ae,as,an,ap,xref,yref), copy(aj,bj,cj,dj) 
!$acc parallel loop gang
      do i=2,nxm1 
          im1=i-1 
          ip1=i+1 
          xmxp=(xref(ip1)-xref(im1))/2.d0 
! 
          aj1=0.d0 
          bj1=0.d0 
          cj1=0.d0 
          dj1=0.d0 
!$acc loop vector reduction(+:aj1,bj1,cj1,dj1)
          do j=2,nym1 
            jm1=j-1 
            jp1=j+1 
            ymyp=(yref(jp1)-yref(jm1))/2.d0 
! 
            aj1=aj1+aw(im1,jm1) 
            bj1=bj1+ap(im1,jm1) 
            if(j.ne.2) bj1=bj1+as(im1,jm1) 
            if(j.ne.nym1) bj1=bj1+an(im1,jm1) 
            cj1=cj1+ae(im1,jm1) 
            dj1=dj1+ar(im1,jm1)-aw(im1,jm1)*p(im1,j)    & 
                    -ae(im1,jm1)*p(ip1,j)-as(im1,jm1)*p(i,jm1)  & 
                    -an(im1,jm1)*p(i,jp1)-ap(im1,jm1)*p(i  ,j) 
! 
          enddo 
          aj(im1)=aj1 
          bj(im1)=bj1 
          cj(im1)=cj1 
          dj(im1)=dj1 
        enddo 
!$acc end parallel loop 
!$acc end data

Alternately, you can try using “kernels” instead of “parallel”. With “parallel” you the programmer tells the compiler which loops to parallelize. However, you only parallelized the outer loop. Adding “vector” to the inner loop should help increase performance.

Note that your performance issue could be due to data movement as well since you’re copying data back and forth each time this loop in encountered. Can you move the data region out farther?

Can you sent the environment variable “PGI_ACC_TIME=1” and post the output? This will provide basic profile information such as how much time was spent copying data and executing the kernel.

Alternatively use Nvidia’s NVVP visual profiler or the command line nprof utility, to view profile information.

Note that I fixed your data region as well. Variables are not allowed to be listed in multiple data clauses, hence I removed aj, bj, cj, and dj from “copyin” and changed “copyout” to “copy”. Granted, you probably don’t need to copy these variables to the device and can save some time changing “copy” back to “copyout”.

  • Mat
3

Hi Mat,

I changed my code according to your suggestion. My error now is 3.1e+11 which is very high.
I used nvprof.exe to profile my code. since PGI_ACC_TIME =1 flag did not give any results. Here is what I get:

C:\Users\Dolf\Desktop\Dyn5>nvprof.exe Dyn5.exe
 SIMULATION STARTED AT: 15:22:15
 SIMULATION ENDED AT:   15:23:06

Warning: ieee_invalid is signaling
Warning: ieee_inexact is signaling
FORTRAN STOP
==6728== Profiling application: Dyn5.exe
==6728== Profiling result:
No kernels were profiled.

==6728== API calls:
No API activities were profiled.
==6728== Warning: Some profiling data are not recorded. Make sure cudaProfilerStop() or cuProfilerStop() is called before application exit to flush profile data.

as you can see, GPU execution time is 50 sec. While CPU can do same job with 0 error in only 38 seconds. I think I am doing something wrong here.

Please advice.
thanks,
Dolf

4

Since there’s no nvprof profile and setting the environment variable PGI_ACC_TIME shows no output, this indicates that no GPU code was executed.

What happens if you set the environment variable “set PGI_ACC_NOTIFY=1”? This will show all the kernel calls.

Also, can you post the output from you compilation? I’m wondering if there’s some type of error.

Please feel free to send a reproducing example to PGI Customer Service (trs@pgroup.com) and I can see what’s going wrong.

  • Mat
5

Hi Mat, happy new year!

here is what the compiler output look like:

------ Rebuild All started: Project: Dynamic5, Configuration: Release x64 ------
Deleting intermediate and output files for project 'Dynamic5', configuration 'Release'
Compiling Project  ...
Common.F90
Kernels.F90
C:\D Drive\CML codes\Dynamic5a\Kernels.F90(739) : warning W0155 : The number of subscripts is less than the rank of cj
  0 inform,   1 warnings,   0 severes, 0 fatal for reyneq_p3_kernel
C:\D Drive\CML codes\Dynamic5a\Kernels.F90(800) : warning W0155 : The number of subscripts is less than the rank of aj
C:\D Drive\CML codes\Dynamic5a\Kernels.F90(802) : warning W0155 : The number of subscripts is less than the rank of bj
C:\D Drive\CML codes\Dynamic5a\Kernels.F90(802) : warning W0155 : The number of subscripts is less than the rank of bj
C:\D Drive\CML codes\Dynamic5a\Kernels.F90(803) : warning W0155 : The number of subscripts is less than the rank of bj
C:\D Drive\CML codes\Dynamic5a\Kernels.F90(803) : warning W0155 : The number of subscripts is less than the rank of bj
C:\D Drive\CML codes\Dynamic5a\Kernels.F90(804) : warning W0155 : The number of subscripts is less than the rank of bj
C:\D Drive\CML codes\Dynamic5a\Kernels.F90(804) : warning W0155 : The number of subscripts is less than the rank of bj
C:\D Drive\CML codes\Dynamic5a\Kernels.F90(805) : warning W0155 : The number of subscripts is less than the rank of cj
C:\D Drive\CML codes\Dynamic5a\Kernels.F90(805) : warning W0155 : The number of subscripts is less than the rank of cj
C:\D Drive\CML codes\Dynamic5a\Kernels.F90(809) : warning W0155 : The number of subscripts is less than the rank of dj
C:\D Drive\CML codes\Dynamic5a\Kernels.F90(809) : warning W0155 : The number of subscripts is less than the rank of dj
  0 inform,  11 warnings,   0 severes, 0 fatal for reyneq_p4_kernel
C:\D Drive\CML codes\Dynamic5a\Kernels.F90(910) : warning W0155 : The number of subscripts is less than the rank of a
C:\D Drive\CML codes\Dynamic5a\Kernels.F90(914) : warning W0155 : The number of subscripts is less than the rank of d
C:\D Drive\CML codes\Dynamic5a\Kernels.F90(914) : warning W0155 : The number of subscripts is less than the rank of gamma
  0 inform,   3 warnings,   0 severes, 0 fatal for tridag_kernel_device
Dynamic.F90
FESusp.F90
Force.F90
Grid.F90
Init.F90
Mass.F90
Misc.F90
Modes.F90
NewmarkBeta.F90
OptionalParams.F90
Output.F90
Rail.F90
Reynolds.F90
reyneq:
    290, Generating copyout(aj(:),bj(:),cj(:),dj(:))
         Generating copyin(ar(:,:),aw(:,:),p(:,:),ae(:,:),as(:,:),an(:,:),ap(:,:),xref(:),yref(:))
    291, Accelerator kernel generated
         Generating Tesla code
        292, !$acc loop gang, vector(128) ! blockidx%x threadidx%x
        307, Sum reduction generated for aj1
        311, Sum reduction generated for cj1
        312, Sum reduction generated for dj1
    302, Loop carried scalar dependence for bj1 at line 308
         Scalar last value needed after loop for bj1 at line 318
Roughness.F90
Stiff.F90
String.F90
Suspension.F90
UserDefGeom.F90
Util.F90
Linking...
Dynamic5 build succeeded.

Build log was saved at "file://C:\D Drive\CML codes\Dynamic5a\x64\Release\BuildLog.htm"

========== Rebuild All: 1 succeeded, 0 failed, 0 skipped ==========

I used the following code instead of your code. Since your code gives me aj matrix error equals to e13 which is extremely high:

!$acc data copyin(aj,bj,cj,dj,ar,aw,p,ae,as,an,ap,xref,yref), copyout(aj,bj,cj,dj)
!$acc parallel loop gang, private(aj1,bj1,cj1,dj1)
		do i=2,nxm1
          im1=i-1
          ip1=i+1
          xmxp=(xref(ip1)-xref(im1))/2.d0
!
          aj(im1)=0.d0
          bj(im1)=0.d0
          cj(im1)=0.d0
          dj(im1)=0.d0

          do j=2,nym1 
            jm1=j-1 
            jp1=j+1 
            ymyp=(yref(jp1)-yref(jm1))/2.d0 
! 
            aj1=aj1+aw(im1,jm1) 
            bj1=bj1+ap(im1,jm1) 
            if(j.ne.2) bj1=bj1+as(im1,jm1) 
            if(j.ne.nym1) bj1=bj1+an(im1,jm1) 
            cj1=cj1+ae(im1,jm1) 
            dj1=dj1+ar(im1,jm1)-aw(im1,jm1)*p(im1,j)    & 
                    -ae(im1,jm1)*p(ip1,j)-as(im1,jm1)*p(i,jm1)  & 
                    -an(im1,jm1)*p(i,jp1)-ap(im1,jm1)*p(i  ,j) 
! 
          enddo 
          aj(im1)=aj1 
          bj(im1)=bj1 
          cj(im1)=cj1 
          dj(im1)=dj1 
        enddo 
!$acc end parallel loop 
!$acc end data

with this code I get zero error (aj(cpu)-aj(gpu) = 0.0). but still the gpu execute in 10 seconds while cpu execute in 6. what bottle neck I can avoid? many thanks,
Dolf

6

Hi Dolf,

Did you mean to have the “aj1”, “bj1”, “cj1”, and “dj1” variable accumulate over multiple iteration of the “i” loop. Since you privatize these variables, the OpenACC version is probably ok since each thread will get it’s own copy, but for the CPU version you might get wrong answers. If this is not what you intended, then I’d recommend initializing these variables in the loop. Also, you shouldn’t need to privatize them. Private variables are stored in global memory which can cause a performance slow down. Otherwise they’ll be local to the kernel and most likely can be stored in registers.

Ideally you’d like to vectorize the inner “j” loop. Though, I’m not sure it will be beneficial here. The problem being that “im1” is your stride-1 dimension so vectorizing the inner loop would lead to poor data access. Is it possible to rearrange your data layout so that all your arrays are accessed “(jm1,im1)”?

Also, are you able to move the copy of the arrays higher up in your program? As it is now, you’ll be copying the arrays back and forth every time you enter this data region.

Even without changing the data layout or optimizing the data movement, I’d give the following a try:

!$acc data copyin(aj,bj,cj,dj,ar,aw,p,ae,as,an,ap,xref,yref), copyout(aj,bj,cj,dj) 
!$acc parallel loop gang
      do i=2,nxm1 
          im1=i-1 
          ip1=i+1 
          xmxp=(xref(ip1)-xref(im1))/2.d0 
! 
          aj(im1)=0.d0 
          bj(im1)=0.d0 
          cj(im1)=0.d0 
          dj(im1)=0.d0 
           aj1=0.d0
           bj1=0.d0
           cj1=0.d0
           dj1=0.d0

!$acc loop vector
          do j=2,nym1 
            jm1=j-1 
            jp1=j+1 
            ymyp=(yref(jp1)-yref(jm1))/2.d0 
! 
            aj1=aj1+aw(im1,jm1) 
            bj1=bj1+ap(im1,jm1) 
            if(j.ne.2) bj1=bj1+as(im1,jm1) 
            if(j.ne.nym1) bj1=bj1+an(im1,jm1) 
            cj1=cj1+ae(im1,jm1) 
            dj1=dj1+ar(im1,jm1)-aw(im1,jm1)*p(im1,j)    & 
                    -ae(im1,jm1)*p(ip1,j)-as(im1,jm1)*p(i,jm1)  & 
                    -an(im1,jm1)*p(i,jp1)-ap(im1,jm1)*p(i  ,j) 
! 
          enddo 
          aj(im1)=aj1 
          bj(im1)=bj1 
          cj(im1)=cj1 
          dj(im1)=dj1 
        enddo 
!$acc end parallel loop 
!$acc end data
  • Mat
7

Hi Mat,

Actually, this code you sent me worked with error in order of e-4. You mentioned about increasing the size of data region, can I do OpenAcc with this code below? this way I will have a whole region of data and I do not need to copy back and forth. As you can see it has calls to another subroutine in the middle (flow(…))

do 300 j=2,nym1
          jm1=j-1
          jp1=j+1
          delyjp1=yref(jp1)-yref(j  )
          delyjm1=yref(j  )-yref(jm1)
          if(j.ne.nym1) delyjp2=yref(j+2)-yref(jp1)
          if(j.ne.2) delyjm2=yref(jm1)-yref(j-2)
          ymyp   =(yref(jp1)-yref(jm1))/2.d0
!
          do 250 i=2,nxm1
            im1=i-1
            ip1=i+1
            delxip1=xref(ip1)-xref(i  )
            delxim1=xref(i  )-xref(im1)
            if(i.ne.nxm1) delxip2=xref(i+2)-xref(ip1)
            if(i.ne.2) delxim2=xref(im1)-xref(i-2)
            xmxp   =(xref(ip1)-xref(im1))/2.d0
!
            h2im = hydnew(i  ,j  )
            h2ip = hydnew(i+1,j  )
            h2jm = hxlnew(i  ,j  )
            h2jp = hxlnew(i  ,j+1)
!
            h2im_b = hyunew(i  ,j  )
            h2ip_b = hyunew(i+1,j  )
            h2jm_b = hxrnew(i  ,j  )
            h2jp_b = hxrnew(i  ,j+1)
!
            ztam=zta(i  ,j  )
            ztap=zta(i  ,j+1)
            etam=eta(i  ,j  )
            etap=eta(i+1,j  )
!
            p2im = (p(im1,j)+p(i,j))/2.d0
            p2ip = (p(ip1,j)+p(i,j))/2.d0
            p2jm = (p(i,jm1)+p(i,j))/2.d0
            p2jp = (p(i,jp1)+p(i,j))/2.d0
!
            pn=p2im*h2im
            call flow(pn,qnim)
            qnh2im = qnim*h2im*h2im
            fmi = h2im*(bearx(im1,j)+bearx(i,j))/2.d0
            dmi=qnh2im/delxim1
            pemi=fmi/dmi
!
            if(etam.eq.1.d0) then
              ami_b=0.d0
              fmi_b=0.d0
            else

              pn_b=p2im*h2im_b
              call flow(pn_b,qnim_b)
              qnh2im_b = qnim_b*h2im_b*h2im_b
              fmi_b = h2im_b*(bearx(im1,j)+bearx(i,j))/2.d0
              dmi_b=qnh2im_b/delxim1
              pemi_b=fmi_b/dmi_b
            endif
!
            pn=p2ip*h2ip
            call flow(pn,qnip)
            qnh2ip = qnip*h2ip*h2ip
            fpi = h2ip*(bearx(ip1,j)+bearx(i,j))/2.d0
            dpi=qnh2ip/delxip1
            pepi=fpi/dpi
!
            if(etap.eq.1.d0) then
              api_b=0.d0
              fpi_b=0.d0
            else
              pn_b=p2ip*h2ip_b
              call flow(pn_b,qnip_b)
              qnh2ip_b = qnip_b*h2ip_b*h2ip_b
              fpi_b = h2ip_b*(bearx(ip1,j)+bearx(i,j))/2.d0
              dpi_b=qnh2ip_b/delxip1
              pepi_b=fpi_b/dpi_b
            endif
!
            pn=p2jm*h2jm
            call flow(pn,qnjm)
            qnh2jm = qnjm*h2jm*h2jm
            fmj = h2jm*(beary(i,jm1)+beary(i,j))/2.d0
            dmj=qnh2jm/delyjm1
            pemj=fmj/dmj
!
            if(ztam.eq.1.d0) then
              amj_b=0.d0
              fmj_b=0.d0
            else
              pn_b=p2jm*h2jm_b
              call flow(pn_b,qnjm_b)
              qnh2jm_b = qnjm_b*h2jm_b*h2jm_b
              fmj_b = h2jm_b*(beary(i,jm1)+beary(i,j))/2.d0
              dmj_b=qnh2jm_b/delyjm1
              pemj_b=fmj_b/dmj_b
            endif
!
            pn=p2jp*h2jp
            call flow(pn,qnjp)
            qnh2jp = qnjp*h2jp*h2jp
            fpj = h2jp*(beary(i,jp1)+beary(i,j))/2.d0
            dpj=qnh2jp/delyjp1
            pepj=fpj/dpj
!
            if(ztap.eq.1.d0) then
              apj_b=0.d0
              fpj_b=0.d0
            else
              pn_b=p2jp*h2jp_b
              call flow(pn_b,qnjp_b)
              qnh2jp_b = qnjp_b*h2jp_b*h2jp_b
              fpj_b = h2jp_b*(beary(i,jp1)+beary(i,j))/2.d0
              dpj_b=qnh2jp_b/delyjp1
              pepj_b=fpj_b/dpj_b
            endif
!
            go to (11,12,13,14,15),idisc
!
!             power law
!
 11           ami=dmax1(0.d0,dmi*(1.d0-0.1d0*dabs(pemi))**5)
              api=dmax1(0.d0,dpi*(1.d0-0.1d0*dabs(pepi))**5)
              amj=dmax1(0.d0,dmj*(1.d0-0.1d0*dabs(pemj))**5)
              apj=dmax1(0.d0,dpj*(1.d0-0.1d0*dabs(pepj))**5)
!
              if(etam.ne.1.d0) then
                ami_b=dmax1(0.d0,dmi_b*(1.d0-0.1d0*dabs(pemi_b))**5)
              endif
              if(etap.ne.1.d0) then
                api_b=dmax1(0.d0,dpi_b*(1.d0-0.1d0*dabs(pepi_b))**5)
              endif
              if(ztam.ne.1.d0) then
                amj_b=dmax1(0.d0,dmj_b*(1.d0-0.1d0*dabs(pemj_b))**5)
              endif
              if(ztap.ne.1.d0) then
                apj_b=dmax1(0.d0,dpj_b*(1.d0-0.1d0*dabs(pepj_b))**5)
              endif
              goto 20
!
!             central difference
!
 12           ami=dmi*(1.d0-0.5d0*dabs(pemi))
              api=dpi*(1.d0-0.5d0*dabs(pepi))
              amj=dmj*(1.d0-0.5d0*dabs(pemj))
              apj=dpj*(1.d0-0.5d0*dabs(pepj))
!
              if(etam.ne.1.d0) then
                ami_b=dmi_b*(1.d0-0.5d0*dabs(pemi_b))
              endif
              if(etap.ne.1.d0) then
                api_b=dpi_b*(1.d0-0.5d0*dabs(pepi_b))
              endif
              if(ztam.ne.1.d0) then
                amj_b=dmj_b*(1.d0-0.5d0*dabs(pemj_b))
              endif
              if(ztap.ne.1.d0) then
                apj_b=dpj_b*(1.d0-0.5d0*dabs(pepj_b))
              endif

              goto 20
!
!             1st-order upwind: idisc = 2
!
 13           ami=dmi
              api=dpi
              amj=dmj
              apj=dpj
!
              if(etam.ne.1.d0) then
                ami_b=dmi_b
              endif
              if(etap.ne.1.d0) then
                api_b=dpi_b
              endif
              if(ztam.ne.1.d0) then
                amj_b=dmj_b
              endif
              if(ztap.ne.1.d0) then
                apj_b=dpj_b
              endif
              goto 20
!
!             hybrid
!
 14           ami=dmax1(0.d0,dmi*(1.0d0-0.5d0*dabs(pemi)))
              api=dmax1(0.d0,dpi*(1.0d0-0.5d0*dabs(pepi)))
              amj=dmax1(0.d0,dmj*(1.0d0-0.5d0*dabs(pemj)))
              apj=dmax1(0.d0,dpj*(1.0d0-0.5d0*dabs(pepj)))
!
              if(etam.ne.1.d0) then
                ami_b=dmax1(0.d0,dmi_b*(1.0d0-0.5d0*dabs(pemi_b)))
              endif
              if(etap.ne.1.d0) then
                api_b=dmax1(0.d0,dpi_b*(1.0d0-0.5d0*dabs(pepi_b)))
              endif
              if(ztam.ne.1.d0) then
                amj_b=dmax1(0.d0,dmj_b*(1.0d0-0.5d0*dabs(pemj_b)))
              endif
              if(ztap.ne.1.d0) then
                apj_b=dmax1(0.d0,dpj_b*(1.0d0-0.5d0*dabs(pepj_b)))
              endif
              goto 20
!
!             exponential
!
 15           ami=dmi*dabs(pemi)/(dexp(dabs(pemi))-1.d0)
              api=dpi*dabs(pepi)/(dexp(dabs(pepi))-1.d0)
              amj=dmj*dabs(pemj)/(dexp(dabs(pemj))-1.d0)
              apj=dpj*dabs(pepj)/(dexp(dabs(pepj))-1.d0)
!
              if(etam.ne.1.d0) then
                ami_b=dmi_b*dabs(pemi_b)/(dexp(dabs(pemi_b))-1.d0)
              endif
              if(etap.ne.1.d0) then
                api_b=dpi_b*dabs(pepi_b)/(dexp(dabs(pepi_b))-1.d0)
              endif
              if(ztam.ne.1.d0) then
                amj_b=dmj_b*dabs(pemj_b)/(dexp(dabs(pemj_b))-1.d0)
              endif
              if(ztap.ne.1.d0) then
                apj_b=dpj_b*dabs(pepj_b)/(dexp(dabs(pepj_b))-1.d0)
              endif
!
 20         continue
!
            aw(im1,jm1)=-ymyp*(etam*(ami+dmax1( fmi,0.d0)) + (1.d0-etam)*(ami_b+dmax1( fmi_b,0.d0)))
            ae(im1,jm1)=-ymyp*(etap*(api+dmax1(-fpi,0.d0)) + (1.d0-etap)*(api_b+dmax1(-fpi_b,0.d0)))
            as(im1,jm1)=-xmxp*(ztam*(amj+dmax1( fmj,0.d0)) + (1.d0-ztam)*(amj_b+dmax1( fmj_b,0.d0)))
            an(im1,jm1)=-xmxp*(ztap*(apj+dmax1(-fpj,0.d0)) + (1.d0-ztap)*(apj_b+dmax1(-fpj_b,0.d0)))
            ap(im1,jm1)=-aw(im1,jm1)-ae(im1,jm1)            &
                        -as(im1,jm1)-an(im1,jm1)            &
                        -ymyp*(etam*fmi+(1.d0-etam)*fmi_b)  &
                        +ymyp*(etap*fpi+(1.d0-etap)*fpi_b)  &
                        -xmxp*(ztam*fmj+(1.d0-ztam)*fmj_b)  &
                        +xmxp*(ztap*fpj+(1.d0-ztap)*fpj_b)
!
            if(idirect.ne.1) then
              amult = xmxp * ymyp * si / dt / omega0
              ar(im1,jm1)=amult*h(i,j)*pold(i,j)
              ap(im1,jm1)=ap(im1,jm1)+amult*hnew(i,j)
            else
              ar(im1,jm1)=0.d0
            endif
!
250       continue
300     continue

Please advice.
Thanks!
Dolf

8

Hi Dolf,

I don’t see any reason why not. Though, I’m just eyeballing it and would need to compile the code to know for sure.

The calls shouldn’t be a problem. You just need to declare them with the OpenACC “routine” directive so that a device callable version is created. This needs to be done in both the body of “flow” as well as in this routine. The former creates the device routine, the later tells the compiler that there is a routine available to call.

For example, in “flow” you’d have something like:

subroutine flow(pn,qnim)
!$acc routine seq
    real pn,qnim

While in this routine you’d add “!$acc routine(flow) seq”. I’m assuming that “flow” doesn’t have an interface. If it did, then you’d put the directive in the interface instead.

The biggest problem I see is that you’re using a computed Goto. We just started supporting computed gotos in OpenACC compute regions in 15.9 or 15.10. Though you might consider changing this obsolete feature to a case statement. Not just for OpenACC, but your own sanity.

  • Mat
9

Hi Mat,
this is what flow subroutine look like:

!=======================================================
         subroutine flow (pn,qn)                                  
!========================================================

    use Dyn_sizes_module
    use master_module
    use config_module
    use flows_module
    use Dyn_module
    implicit none
	
!$acc routine seq
	real(8) :: C22, Q2, QN1, QN2, S1, U1, FF0, XI, DEL, AIJ, C12, C11, DEXP, DLOG10, DFLOAT,    &
	           V1, V2, V3, V4, V5, PN, Z1, Z2, A, B, R1, R2, V, EV, F1, F2, Z0, Z, DLOG, ALZ, QN
	integer :: I, LOC
	    
    dimension a(20),b(20)
!
!ha    use the continuum model.....
       if (iqpo.eq.0) then
         qn   = pn
         return
!
!ha    use the first order slip model....
       else if (iqpo.eq.1) then
         qn   = pn + t1
         return
!
!ha    use the second order slip model.....
       else if (iqpo.eq.2) then
         r1   = t2/pn
         r2   = r1/pn
         qn   = pn + t1 + r1
         return
!
!ha    use the asymtotic fk model.....
       else if (iqpo.eq.3) then
         r1   = t2/pn
         s1   = t3/(pn*pn)
         u1   = t4/(pn*pn*pn)
         qn   = pn + t1 + r1 - s1 - u1
         return
!
!ha    use the full fk model.....
       else if (iqpo.eq.4) then
         z  = d0*pn
         if (icoe.eq.1) go to 15
         a(1) = 0.d0
         a(2) = -1.d0
         b(1) = -pir
         b(2) = 1.5d0*(1.d0-gama)
         do 10  i = 3,nter
              xi  = dfloat(i)
              aij = xi*(xi-1.d0)*(xi-2.d0)
              a(i) = (-2.d0*a(i-2))/aij
              b(i) = (-2.d0*b(i-2)-(3.d0*xi*xi-6.d0*xi+2.d0)*a(i))/aij
  10    continue

         icoe = 1
  15    if (z.ge.1.1d0)  then

         v = 1.889881575d0*z**0.66666666666666666d0
         v1 = 12.d0*v
         v2 = 24.d0*v*v1
         v3 = 36.d0*v*v2
         v4 = 48.d0*v*v3
         v5 = 60.d0*v*v4
         ev = pit*dexp(-v)
         ff0 = ev*(1.d0-1.d0/v1+25.d0/v2-1225.d0/v3 + 89425.d0/v4-7263025.d0/v5)
         f1 = ev*dsqrt(v/3.d0)*(1.d0+5.d0/v1-35.d0/v2 + 665.d0/v3+9625.d0/v4-9284275.d0/v5)
         f2 = ev*(v/3.d0)*(1.d0+17.d0/v1-35.d0/v2 + 1925.d0/v3-175175.d0/v4+22247225.d0/v5)
         else

         ff0   = 0.d0
         f1   = 0.d0
         f2   = 0.d0
         alz  = dlog(z)
         do 20  i = nter,1,-1
              xi  = dfloat(i)
              aij = 1.d0/(1.d0+xi)
              if (i.eq.1) then
                   ff0 = ((alz*xi+1.d0)*a(i) + b(i)*xi + ff0)
                   go to 12

              end if

              ff0 = ((alz*xi+1.d0)*a(i) + b(i)*xi + ff0)*z
   12         f1 = (a(i)*alz + b(i) + f1)*z

              f2 = (aij*((alz-aij)*a(i)+b(i)) + f2)*z

   20    continue
         ff0 = -0.5d0*ff0
         f1 = 0.5d0*(f1 + 1.d0)
         f2 = pir/4.d0 - 0.5d0*(f2 + 1.d0)*z
         end if
         c11 = 8.d0-z*z*z*(pir/12.d0-z/16.d0)-2.d0*z*(4.d0+z*z)*ff0 - (16.d0+z*z*(8.d0+z*z/8.d0))*f1-z*(16.d0+z*z)*f2
         c22 = 1.d0- 2.d0*f1
         c12 = 2.d0 - (pir/2.d0)*z + z*z/4.d0-2.d0*z*ff0 - (4.d0 +z*z/2.d0)*f1 - 2.d0*z*f2
         del = c11*c22 - c12*c12

         q2 = (pir/del)*(c11 - z*z*(c12/6.d0-z*z*c22/144.d0))
         qn = (-1.d0/z+q2)*(6.d0/z)*pn

         return
!
!
!ha    use the data base of precalculated qp based on fk model.....
       else if (iqpo.eq.5) then
         z0=d0*pn
         loc=dint(200.d0*dlog10(z0)+401)
         if (loc.ge.801) goto 55
         if(loc.lt.1)goto 56
         z1=zdat(loc)
!
         qn1=qndat(loc)
         z2=zdat(loc+1)
         qn2=qndat(loc+1)
!
!ha      interpolate.....
         qn=(qn2-qn1)*(z0-z1)/(z2-z1)+qn1
         return
!
!        if inverse knudsen no. is out of range of database
!        use first order slip
 55      continue
         r1   = t2/pn
         s1   = t3/(pn*pn)
         u1   = t4/(pn*pn*pn)
         qn   = pn + t1 + r1 - s1 - u1
         return
 56      continue
         qn=-pn*6.d0/pir*dlog(z0)/z0
         return

       end if
end

here is the reynolds subroutine:


!======================================================
        subroutine reyneq(idirect)
!======================================================

    use Dyn_sizes_module
	use master_module
	use config_module
	use sl_mesh_module
	use filmtk_module
	use flows_module
	use average_module
	use bearing_module
	use roughness_module
	use reynolds_module
	use Dyn_module
	! device modules 
	use kernels_sub
	use reyneq_Dev
	use Q4_globals_Dev
	use flows_Dev
	use average_Dev
	use filmtk_Dev
	use bearing_Dev
	use openacc
    implicit none
!$acc routine(flow) seq
	real(8) :: H2IP_B, AP2, AP3, AP1, AP4, APJ_B, RATIO, DEXP, AMI_B, RAK, H2JP, AW4, AW3, AW2, AW1, &
	           BJ, QNJP_B, PEMI_B, PEPJ, H2IM, APJ, H2IP, API, H2JP_B, DABS, PEPJ_B, H2JM, PEMJ_B, DMI, DMJ, &
	           AN4, AN1, AN2, AN3, PEPI_B, DPI_B, AMI, AMJ, PN_B, API_B, AMJ_B, PN, H2JM_B, AJ, RAKPRE, &
	           FPJ, AE1, AE3, AE2, AE4, QNIM_B, P2JM, FMI_B, QNJP, DELYJM2, DELYJM1, QNH2JM, AMULT, DPJ_B, &
	           FMJ_B, AKN, DJ, AKD, P2IM, DELXIM2, DELXIM1, FPJ_B, P2IP, QNH2IM_B, AS3, CJ, AS1, DMI_B, AS4, &
	           QNH2JP, FMJ, FMI, ZTAM, QNH2JP_B, ETAP, FPI_B, DELYJP1, DELYJP2, ETAM, AR1, AR2, AR3, AR4, &
	           AS2, QNJM_B, XMXP, DPJ, DPI, P2JP, QNH2IM, DELXIP1, DELXIP2, QNIP, QNH2JM_B, H2IM_B, QNIM, QNH2IP, &
	           PEPI, QNH2IP_B, AE, DMJ_B, FPI, AN, AP, AS, AR, AW, DP4, DP3, DP2, DP1, QNIP_B, YMYP, PEMJ, &
	           ZTAP, PEMI, QNJM
	integer :: NY1M1, IP1, NY4, JP1, NX5, NX4, NX1, NX3, NX2, I1, I2, IM1, KINT, JM1, I, K, J, L, &
	           IDIRECT, NX1M1, NY2, NY3, NY1, J1, J2, NY5
	real(8) :: a,b,akdh(nxmax,nymax),aknh(nxmax,nymax),ajh(nxmax,nymax),bjh(nxmax,nymax),cjh(nxmax,nymax),djh(nxmax,nymax)
	real(8), device, allocatable :: aj1Dev(:),bj1Dev(:),cj1Dev(:),dj1Dev(:),ajaDev(:),awaDev(:,:)
	real(8) :: aj1,bj1,cj1,dj1
	real(8), allocatable :: awa(:,:),aja(:)
	integer :: s
	dimension a(nxmax,nymax),b(nxmax)
    
!        integer, parameter :: nxmax1=520, nymax1=520, nxmax2=260, nymax2=260,     &
!                  nxmax3=140, nymax3=140, nxmax4=70, nymax4=70, nxmax5=40, nymax5=40
! commented out by Dolf 7/23/15
        dimension aw(nxmax,nymax),ap(nxmax,nymax),ae(nxmax,nymax), &
                  ar(nxmax,nymax),as(nxmax,nymax),an(nxmax,nymax), &
                  aj(nxmax),bj(nxmax),cj(nxmax),dj(nxmax)
        dimension aw1(nxmax1,nymax1),ap1(nxmax1,nymax1), &
                  ae1(nxmax1,nymax1),as1(nxmax1,nymax1), &
                  an1(nxmax1,nymax1),ar1(nxmax1,nymax1), &
                  dp1(nxmax1,nymax1)  
        dimension aw2(nxmax2,nymax2),ap2(nxmax2,nymax2), &
                  ae2(nxmax2,nymax2),as2(nxmax2,nymax2), &
                  an2(nxmax2,nymax2),ar2(nxmax2,nymax2), &
                  dp2(nxmax2,nymax2)
       dimension aw3(nxmax3,nymax3),ap3(nxmax3,nymax3), &
                  ae3(nxmax3,nymax3),as3(nxmax3,nymax3), &
                  an3(nxmax3,nymax3),ar3(nxmax3,nymax3), &
                  dp3(nxmax3,nymax3)
        dimension aw4(nxmax4,nymax4),ap4(nxmax4,nymax4), &
                  ae4(nxmax4,nymax4),as4(nxmax4,nymax4), &
                  an4(nxmax4,nymax4),ar4(nxmax4,nymax4), &
                  dp4(nxmax4,nymax4)
!     BC - Level 5 is no longer used
!        dimension aw5(nxmax5,nymax5),ap5(nxmax5,nymax5), &
!                  ae5(nxmax5,nymax5),as5(nxmax5,nymax5), &
!                  an5(nxmax5,nymax5),ar5(nxmax5,nymax5), &
!                  dp5(nxmax5,nymax5)
!
        nx1 = 2 + (nx-2)/2
        ny1 = 2 + (ny-2)/2
        nx2 = 2 + (nx1-2)/2
        ny2 = 2 + (ny1-2)/2
        nx3 = 2 + (nx2-2)/2
        ny3 = 2 + (ny2-2)/2
        nx4 = 2 + (nx3-2)/2
        ny4 = 2 + (ny3-2)/2
		!allocate(aj1Dev(nxmax),bj1Dev(nxmax),cj1Dev(nxmax),dj1Dev(nxmax))
		!allocate(ajaDev(10))
		!allocate(awaDev(10,10))
		!allocate(awa(10,10),aja(10))
		!awa = 1.0
		!aja = 0.0
		!awaDev = 1.0
		!ajaDev = 0.0
!       calculate:
!       1) the flow rarefaction factors qn
!       2) the average flow factor of rough bearing surfaces
!
		pitDev = pit
		pirDev = pir
		
		gamaDev = gama
		d0Dev = d0
		siDev = si
		dtDev = dt
		
		omega0Dev = omega0
		        
		t1Dev = t1
		t2Dev = t2
		t3Dev = t3
		t4Dev = t4

		zdatDev = zdat
		qndatDev = qndat
		xrefDev = xref
		yrefDev = yref

		pDev = p
		poldDev = pold
		hDev = h
		hyunew = hyunewDev
	    nreyneq=0
5		nreyneq=nreyneq+1
!	
		! added by Dolf 6/2/2015
		! reyneq runs on GPU. 
		! p1_kernel starts here:
		! disabling p1_kernel due to errors: 10/
		
		!grid = dim3(ceiling(real(nx-1)/threads%x), &
		!			ceiling(real(ny-1)/threads%y),1)  !ny-1
		!call reyneq_p1_kernel<<<grid,threads>>>(nx,ny,nxmax,nymax,nter,iqpo,icoe,idisc, &
		!idirect,pitDev,pirDev,gamaDev,d0Dev,siDev,dtDev,omega0Dev,t1Dev,t2Dev,t3Dev,t4Dev,&
		!zdatDev,qndatDev,xrefDev,yrefDev,pDev,poldDev,hDev,hnewDev,awDev,aeDev,asDev,&
		!anDev,arDev,apDev,bearxDev,bearyDev,hydnewDev,hyunewDev,hxlnewDev,hxrnewDev,ztaDev,etaDev)
		!istat = cudaThreadSynchronize()
		!istat = cudaDeviceSynchronize()
		!if (istat .ne. 0) write(*,*) ' reyneq_p1 kernel error ',cudaGetErrorString(istat),istat
! reyeq_p1 starts here, OpenAcc directives
! reyenq_p1
!$acc data copyin(ar,aw,p,ae,as,an,ap,xref,yref,hydnew,hyunew,hxlnew,hxrnew,zta,eta,bearx,beary), copyout(aj,bj,cj,dj,p) 
!$acc parallel loop gang 
        do 300 j=2,nym1
          jm1=j-1
          jp1=j+1
          delyjp1=yref(jp1)-yref(j  )
          delyjm1=yref(j  )-yref(jm1)
          if(j.ne.nym1) delyjp2=yref(j+2)-yref(jp1)
          if(j.ne.2) delyjm2=yref(jm1)-yref(j-2)
          ymyp   =(yref(jp1)-yref(jm1))/2.d0
!
          do 250 i=2,nxm1
            im1=i-1
            ip1=i+1
            delxip1=xref(ip1)-xref(i  )
            delxim1=xref(i  )-xref(im1)
            if(i.ne.nxm1) delxip2=xref(i+2)-xref(ip1)
            if(i.ne.2) delxim2=xref(im1)-xref(i-2)
            xmxp   =(xref(ip1)-xref(im1))/2.d0
!
            h2im = hydnew(i  ,j  )
            h2ip = hydnew(i+1,j  )
            h2jm = hxlnew(i  ,j  )
            h2jp = hxlnew(i  ,j+1)
!
            h2im_b = hyunew(i  ,j  )
            h2ip_b = hyunew(i+1,j  )
            h2jm_b = hxrnew(i  ,j  )
            h2jp_b = hxrnew(i  ,j+1)
!
            ztam=zta(i  ,j  )
            ztap=zta(i  ,j+1)
            etam=eta(i  ,j  )
            etap=eta(i+1,j  )
!
            p2im = (p(im1,j)+p(i,j))/2.d0
            p2ip = (p(ip1,j)+p(i,j))/2.d0
            p2jm = (p(i,jm1)+p(i,j))/2.d0
            p2jp = (p(i,jp1)+p(i,j))/2.d0
!
            pn=p2im*h2im
            call flow(pn,qnim)
            qnh2im = qnim*h2im*h2im
            fmi = h2im*(bearx(im1,j)+bearx(i,j))/2.d0
            dmi=qnh2im/delxim1
            pemi=fmi/dmi
!
            if(etam.eq.1.d0) then
              ami_b=0.d0
              fmi_b=0.d0
            else

              pn_b=p2im*h2im_b
              call flow(pn_b,qnim_b)
              qnh2im_b = qnim_b*h2im_b*h2im_b
              fmi_b = h2im_b*(bearx(im1,j)+bearx(i,j))/2.d0
              dmi_b=qnh2im_b/delxim1
              pemi_b=fmi_b/dmi_b
            endif
!
            pn=p2ip*h2ip
            call flow(pn,qnip)
            qnh2ip = qnip*h2ip*h2ip
            fpi = h2ip*(bearx(ip1,j)+bearx(i,j))/2.d0
            dpi=qnh2ip/delxip1
            pepi=fpi/dpi
!
            if(etap.eq.1.d0) then
              api_b=0.d0
              fpi_b=0.d0
            else
              pn_b=p2ip*h2ip_b
              call flow(pn_b,qnip_b)
              qnh2ip_b = qnip_b*h2ip_b*h2ip_b
              fpi_b = h2ip_b*(bearx(ip1,j)+bearx(i,j))/2.d0
              dpi_b=qnh2ip_b/delxip1
              pepi_b=fpi_b/dpi_b
            endif
!
            pn=p2jm*h2jm
            call flow(pn,qnjm)
            qnh2jm = qnjm*h2jm*h2jm
            fmj = h2jm*(beary(i,jm1)+beary(i,j))/2.d0
            dmj=qnh2jm/delyjm1
            pemj=fmj/dmj
!
            if(ztam.eq.1.d0) then
              amj_b=0.d0
              fmj_b=0.d0
            else
              pn_b=p2jm*h2jm_b
              call flow(pn_b,qnjm_b)
              qnh2jm_b = qnjm_b*h2jm_b*h2jm_b
              fmj_b = h2jm_b*(beary(i,jm1)+beary(i,j))/2.d0
              dmj_b=qnh2jm_b/delyjm1
              pemj_b=fmj_b/dmj_b
            endif
!
            pn=p2jp*h2jp
            call flow(pn,qnjp)
            qnh2jp = qnjp*h2jp*h2jp
            fpj = h2jp*(beary(i,jp1)+beary(i,j))/2.d0
            dpj=qnh2jp/delyjp1
            pepj=fpj/dpj
!
            if(ztap.eq.1.d0) then
              apj_b=0.d0
              fpj_b=0.d0
            else
              pn_b=p2jp*h2jp_b
              call flow(pn_b,qnjp_b)
              qnh2jp_b = qnjp_b*h2jp_b*h2jp_b
              fpj_b = h2jp_b*(beary(i,jp1)+beary(i,j))/2.d0
              dpj_b=qnh2jp_b/delyjp1
              pepj_b=fpj_b/dpj_b
            endif
!
            go to (11,12,13,14,15),idisc
!
!             power law
!
 11           ami=dmax1(0.d0,dmi*(1.d0-0.1d0*dabs(pemi))**5)
              api=dmax1(0.d0,dpi*(1.d0-0.1d0*dabs(pepi))**5)
              amj=dmax1(0.d0,dmj*(1.d0-0.1d0*dabs(pemj))**5)
              apj=dmax1(0.d0,dpj*(1.d0-0.1d0*dabs(pepj))**5)
!
              if(etam.ne.1.d0) then
                ami_b=dmax1(0.d0,dmi_b*(1.d0-0.1d0*dabs(pemi_b))**5)
              endif
              if(etap.ne.1.d0) then
                api_b=dmax1(0.d0,dpi_b*(1.d0-0.1d0*dabs(pepi_b))**5)
              endif
              if(ztam.ne.1.d0) then
                amj_b=dmax1(0.d0,dmj_b*(1.d0-0.1d0*dabs(pemj_b))**5)
              endif
              if(ztap.ne.1.d0) then
                apj_b=dmax1(0.d0,dpj_b*(1.d0-0.1d0*dabs(pepj_b))**5)
              endif
              goto 20
!
!             central difference
!
 12           ami=dmi*(1.d0-0.5d0*dabs(pemi))
              api=dpi*(1.d0-0.5d0*dabs(pepi))
              amj=dmj*(1.d0-0.5d0*dabs(pemj))
              apj=dpj*(1.d0-0.5d0*dabs(pepj))
!
              if(etam.ne.1.d0) then
                ami_b=dmi_b*(1.d0-0.5d0*dabs(pemi_b))
              endif
              if(etap.ne.1.d0) then
                api_b=dpi_b*(1.d0-0.5d0*dabs(pepi_b))
              endif
              if(ztam.ne.1.d0) then
                amj_b=dmj_b*(1.d0-0.5d0*dabs(pemj_b))
              endif
              if(ztap.ne.1.d0) then
                apj_b=dpj_b*(1.d0-0.5d0*dabs(pepj_b))
              endif

              goto 20
!
!             1st-order upwind: idisc = 2
!
 13           ami=dmi
              api=dpi
              amj=dmj
              apj=dpj
!
              if(etam.ne.1.d0) then
                ami_b=dmi_b
              endif
              if(etap.ne.1.d0) then
                api_b=dpi_b
              endif
              if(ztam.ne.1.d0) then
                amj_b=dmj_b
              endif
              if(ztap.ne.1.d0) then
                apj_b=dpj_b
              endif
              goto 20
!
!             hybrid
!
 14           ami=dmax1(0.d0,dmi*(1.0d0-0.5d0*dabs(pemi)))
              api=dmax1(0.d0,dpi*(1.0d0-0.5d0*dabs(pepi)))
              amj=dmax1(0.d0,dmj*(1.0d0-0.5d0*dabs(pemj)))
              apj=dmax1(0.d0,dpj*(1.0d0-0.5d0*dabs(pepj)))
!
              if(etam.ne.1.d0) then
                ami_b=dmax1(0.d0,dmi_b*(1.0d0-0.5d0*dabs(pemi_b)))
              endif
              if(etap.ne.1.d0) then
                api_b=dmax1(0.d0,dpi_b*(1.0d0-0.5d0*dabs(pepi_b)))
              endif
              if(ztam.ne.1.d0) then
                amj_b=dmax1(0.d0,dmj_b*(1.0d0-0.5d0*dabs(pemj_b)))
              endif
              if(ztap.ne.1.d0) then
                apj_b=dmax1(0.d0,dpj_b*(1.0d0-0.5d0*dabs(pepj_b)))
              endif
              goto 20
!
!             exponential
!
 15           ami=dmi*dabs(pemi)/(dexp(dabs(pemi))-1.d0)
              api=dpi*dabs(pepi)/(dexp(dabs(pepi))-1.d0)
              amj=dmj*dabs(pemj)/(dexp(dabs(pemj))-1.d0)
              apj=dpj*dabs(pepj)/(dexp(dabs(pepj))-1.d0)
!
              if(etam.ne.1.d0) then
                ami_b=dmi_b*dabs(pemi_b)/(dexp(dabs(pemi_b))-1.d0)
              endif
              if(etap.ne.1.d0) then
                api_b=dpi_b*dabs(pepi_b)/(dexp(dabs(pepi_b))-1.d0)
              endif
              if(ztam.ne.1.d0) then
                amj_b=dmj_b*dabs(pemj_b)/(dexp(dabs(pemj_b))-1.d0)
              endif
              if(ztap.ne.1.d0) then
                apj_b=dpj_b*dabs(pepj_b)/(dexp(dabs(pepj_b))-1.d0)
              endif
!
 20         continue
!
            aw(im1,jm1)=-ymyp*(etam*(ami+dmax1( fmi,0.d0)) + (1.d0-etam)*(ami_b+dmax1( fmi_b,0.d0)))
            ae(im1,jm1)=-ymyp*(etap*(api+dmax1(-fpi,0.d0)) + (1.d0-etap)*(api_b+dmax1(-fpi_b,0.d0)))
            as(im1,jm1)=-xmxp*(ztam*(amj+dmax1( fmj,0.d0)) + (1.d0-ztam)*(amj_b+dmax1( fmj_b,0.d0)))
            an(im1,jm1)=-xmxp*(ztap*(apj+dmax1(-fpj,0.d0)) + (1.d0-ztap)*(apj_b+dmax1(-fpj_b,0.d0)))
            ap(im1,jm1)=-aw(im1,jm1)-ae(im1,jm1)            &
                        -as(im1,jm1)-an(im1,jm1)            &
                        -ymyp*(etam*fmi+(1.d0-etam)*fmi_b)  &
                        +ymyp*(etap*fpi+(1.d0-etap)*fpi_b)  &
                        -xmxp*(ztam*fmj+(1.d0-ztam)*fmj_b)  &
                        +xmxp*(ztap*fpj+(1.d0-ztap)*fpj_b)
!
            if(idirect.ne.1) then
              amult = xmxp * ymyp * si / dt / omega0
              ar(im1,jm1)=amult*h(i,j)*pold(i,j)
              ap(im1,jm1)=ap(im1,jm1)+amult*hnew(i,j)
            else
              ar(im1,jm1)=0.d0
            endif
!
250       continue
300     continue
!$acc end parallel loop
!       ! reyneq_p1_kernel ends here

        akd=0.d0
        akn=0.d0
		akdDev = 0.d0
		aknDev = 0.d0
		
		!p = pDev
		!aw = awDev
		!ae = aeDev
		!as = asDev
		!an = anDev
		!ap = apDev
		!ar = arDev
		
		!do j=1,ny
        !    write(105,'(10000e23.15)')(ap(i,j)-1.d0,i=1,nx)
        !enddo

        ! added by Dolf 6/9/15
		! reyneq_p2_kernel starts here
		!grid = dim3(ceiling(real(nx-1)/threads%x), &
		!			ceiling(real(ny-1)/threads%y),1)  !ny-1
		!call reyneq_p2_kernel<<<grid,threads>>>(nx,ny,nxmax,nymax,pDev,ajDev,bjDev,cjDev,djDev, &
		!awDev,aeDev,asDev,anDev,apDev,arDev,akdDev,aknDev)
		!istat = cudaThreadSynchronize()
		!istat = cudaDeviceSynchronize()
		!if (istat .ne. 0) write(*,*) ' reyneq_p2 kernel error ',cudaGetErrorString(istat)
! reyeq_p2 starts here

!$acc parallel loop gang 
do j=2,nym1
          jm1=j-1
          jp1=j+1
!$acc loop vector 
          do i=2,nxm1
            im1=i-1
            ip1=i+1
            aj(im1)=aw(im1,jm1)
            bj(im1)=ap(im1,jm1)
            cj(im1)=ae(im1,jm1)
            dj(im1)=ar(im1,jm1)-as(im1,jm1)*p(i,jm1) - an(im1,jm1)*p(i,jp1)
            if(i.eq.2) then
              dj(im1)=dj(im1)-aw(im1,jm1)*p(im1,j)
              aj(im1)=0.d0
            else if (i.eq.nxm1) then
              dj(im1)=dj(im1)-ae(im1,jm1)*p(ip1,j)
              cj(im1)=0.d0
            endif
            akd=akd+dabs(aj(im1)*p(im1,j)+bj(im1)*p(i,j) + cj(im1)*p(ip1,j)-dj(im1))
            akn=akn+dabs(bj(im1)*p(i,j))
          enddo
        enddo
!$acc end parallel loop
!reyneq_p2 end
		! reyneq_p2_kernel ends here
!
	!akd = 0.d0
	!akn = 0.d0
	!akdh = akdDev
	!aknh = aknDev
	!do i=2,nx-1
!		do j=2,ny-1
!		akd = akd + akdh(i,j)
!		akn = akn + aknh(i,j)
!		enddo
!	enddo
	!akd = akdDev
	!akn = aknDev
	ak  = akd/akn
	!write(*,*)'idirect=',idirect
	write(*,*)'ak=',ak
	
        if((mod(nreyneq,5).eq.0)) then
          write(6,990)t,nreyneq,ak
990       format('  T(s)=',g12.6,',Iteration=',i3,',Residual=',g12.6)
        end if
	

!C        if(ak.lt.akmax.or.nreyneq.gt.nitmax) return
!	Bug Fix
	if(nreyneq.gt.1.and.(ak.lt.akmax.or.nreyneq.gt.nitmax))return
!
	rakpre=ak
	kint=0
 50     kint=kint+1
!
!       first sweep in x-direction
!
        ! added by Dolf 6/11/15
		! reyneq_p3_kernel starts here
		! returned P3 here due to problems (race condition)
		
		!grid = dim3(ceiling(real(nx-1)/threads%x), &
		!			ceiling(real(ny-1)/threads%y),1)  !ny-1 
		!call reyneq_p3_kernel<<<grid,threads>>>(nx,ny,nxmax,nymax,pDev,xrefDev,yrefDev, &
		!awDev,apDev,aeDev,arDev,asDev,anDev,ajDev,bjDev,cjDev,djDev,betaDev,gammaDev)
		!istat = cudaDeviceSynchronize()
		!if (istat .ne. 0) write(*,*) ' reyneq_p3 kernel error ',cudaGetErrorString(istat)
		!open(100, file='aw0d5.dat', status='unknown')
		!do j=1,ny
        !    write(100,'(10000e23.15)')(aw(i,j),i=1,nx)
        !enddo
		!close(100)
		!open(100, file='ae0d5.dat', status='unknown')
		!do j=1,ny
        !    write(100,'(10000e23.15)')(ae(i,j),i=1,nx)
        !enddo
		!close(100)
		!open(100, file='an0d5.dat', status='unknown')
		!do j=1,ny
        !    write(100,'(10000e23.15)')(an(i,j),i=1,nx)
        !enddo
		!close(100)
		!open(100, file='as0d5.dat', status='unknown')
		!do j=1,ny
        !    write(100,'(10000e23.15)')(as(i,j),i=1,nx)
        !enddo
		!close(100)
		!open(100, file='ap0d5.dat', status='unknown')
		!do j=1,ny
        !    write(100,'(10000e23.15)')(ap(i,j),i=1,nx)
        !enddo
		!close(100)
		!open(100, file='ar0d5.dat', status='unknown')
		!do j=1,ny
        !    write(100,'(10000e23.15)')(ar(i,j),i=1,nx)
        !enddo
		!close(100)
!reyneq_p3 start
		aj = 0.d0
		bj = 0.d0
		cj = 0.d0
		dj = 0.d0

		do 500 j=2,nym1
            jm1=j-1
            jp1=j+1
            ymyp=(yref(jp1)-yref(jm1))/2.d0
!
            do 450 i=2,nxm1
              im1=i-1
              ip1=i+1
              xmxp=(xref(ip1)-xref(im1))/2.d0
!
              aj(im1)=aw(im1,jm1)
              bj(im1)=ap(im1,jm1)
              cj(im1)=ae(im1,jm1)
              dj(im1)=ar(im1,jm1)-as(im1,jm1)*p(i,jm1) - an(im1,jm1)*p(i,jp1)
!
              if(i.eq.2) then
                dj(im1)=dj(im1)-aw(im1,jm1)*p(im1,j)
                aj(im1)=0.d0
              else if (i.eq.nxm1) then
                dj(im1)=dj(im1)-ae(im1,jm1)*p(ip1,j)
                cj(im1)=0.d0
              endif
!
450         continue
            call tridag(nxm2,aj,bj,cj,dj)
            do 475 i=1,nxm2
              p(i+1,j)=dj(i)
475         continue

500       continue
! end reyneq_p3
		!p = pDev
			
		
		
        ! added by Dolf 6/12/15
		! _p4_kernel starts here
		pDev = p
		!aj1Dev = aj
		!bj1Dev = bj
		!cj1Dev = cj
		!dj1Dev = dj
		!cpu version of p4
		!open acc directives
! data copyin(aj,bj,cj,dj,ar,aw,p,ae,as,an,ap,xref,yref), copyout(aj,bj,cj,dj) 
!$acc parallel loop gang 
      do i=2,nxm1 
          im1=i-1 
          ip1=i+1 
          xmxp=(xref(ip1)-xref(im1))/2.d0 
! 
          aj(im1)=0.d0 
          bj(im1)=0.d0 
          cj(im1)=0.d0 
          dj(im1)=0.d0 
           aj1=0.d0 
           bj1=0.d0 
           cj1=0.d0 
           dj1=0.d0 

!$acc loop vector 
          do j=2,nym1 
            jm1=j-1 
            jp1=j+1 
            ymyp=(yref(jp1)-yref(jm1))/2.d0 
! 
            aj1=aj1+aw(im1,jm1) 
            bj1=bj1+ap(im1,jm1) 
            if(j.ne.2) bj1=bj1+as(im1,jm1) 
            if(j.ne.nym1) bj1=bj1+an(im1,jm1) 
            cj1=cj1+ae(im1,jm1) 
            dj1=dj1+ar(im1,jm1)-aw(im1,jm1)*p(im1,j)    & 
                    -ae(im1,jm1)*p(ip1,j)-as(im1,jm1)*p(i,jm1)  & 
                    -an(im1,jm1)*p(i,jp1)-ap(im1,jm1)*p(i  ,j) 
! 
          enddo 
          aj(im1)=aj1 
          bj(im1)=bj1 
          cj(im1)=cj1 
          dj(im1)=dj1 
        enddo 
!$acc end parallel loop 
!$acc end data



I’m assuming that “flow” doesn’t have an interface. If it did, then you’d put the directive in the interface instead.

what do you mean? please look at flow subroutine above and tell me if it’s interface or not.

The biggest problem I see is that you’re using a computed Goto.

why would it be a problem?

Though you might consider changing this obsolete feature to a case statement.

how would I change it to case statements?

here is the output of the compiler when I try to compile the code. It fails actually.

------ Rebuild All started: Project: Dynamic5, Configuration: Release x64 ------
Deleting intermediate and output files for project 'Dynamic5', configuration 'Release'
Compiling Project  ...
Common.F90
Kernels.F90
Dynamic.F90
FESusp.F90
Force.F90
Grid.F90
Init.F90
Mass.F90
Misc.F90
Modes.F90
NewmarkBeta.F90
OptionalParams.F90
Output.F90
Rail.F90
Reynolds.F90
C:\D Drive\CML codes\Dynamic5a\Reynolds.F90(138) : error S0155 : Invalid accelerator data region: branching into or out of region is not allowed 
reyneq:
    138, Invalid accelerator data region: branching into or out of region is not allowed
    139, Accelerator kernel generated
         Generating Tesla code
        140, !$acc loop gang ! blockidx%x
    139, Generating copyin(yref(:),hnew(:,:))
         Generating copy(ar(:,:))
         Generating copyin(h(:,:),pold(:,:))
         Generating copy(qnjp_b,qnjp,qnjm_b)
         Generating copyin(beary(:,:))
         Generating copy(qnjm,qnip_b,qnip,pn_b,qnim_b)
         Generating copyin(bearx(:,:))
         Generating copy(qnim,pn)
         Generating copyin(p(:,:),eta(:,:),zta(:,:),hxrnew(:,:),hyunew(:,:),hxlnew(:,:),hydnew(:,:),xref(:))
         Generating copy(aw(:,:),ae(:,:),as(:,:),an(:,:),ap(:,:))
    140, Accelerator restriction: scalar variable live-out from loop: pn_b,pn
    149, Loop carried scalar dependence for ami_b,dmi_b,pemi_b,api_b,dpi_b,pepi_b,amj_b,dmj_b,pemj_b,apj_b,dpj_b,pepj_b at line 307
         Accelerator restriction: scalar variable live-out from loop: pn_b,pn
    417, Accelerator kernel generated
         Generating Tesla code
        418, !$acc loop gang ! blockidx%x
        422, !$acc loop vector(128) ! threadidx%x
    417, Generating copyin(p(1:nxm1+1,1:nym1+1),aw(:nxm1-1,:nym1-1))
         Generating copy(aj(:nxm1-1))
         Generating copyin(ap(:nxm1-1,:nym1-1))
         Generating copy(bj(:nxm1-1))
         Generating copyin(ae(:nxm1-1,:nym1-1))
         Generating copy(cj(:nxm1-1))
         Generating copyin(ar(:nxm1-1,:nym1-1),as(:nxm1-1,:nym1-1),an(:nxm1-1,:nym1-1))
         Generating copy(dj(:nxm1-1))
    422, Loop is parallelizable
    567, Accelerator kernel generated
         Generating Tesla code
        568, !$acc loop gang ! blockidx%x
        583, !$acc loop vector(128) ! threadidx%x
    567, Generating copyout(aj(:nxm1-1),bj(:nxm1-1),cj(:nxm1-1),dj(:nxm1-1))
         Generating copyin(p(1:nxm1+1,1:nym1+1),ar(:nxm1-1,:nym1-1),ae(:nxm1-1,:nym1-1),an(:nxm1-1,:nym1-1),ap(:nxm1-1,:nym1-1),aw(:nxm1-1,:nym1-1),as(:nxm1-1,:nym1-1))
    583, Scalar last value needed after loop for bj1 at line 599
         Accelerator restriction: scalar variable live-out from loop: bj1
  0 inform,   0 warnings,   1 severes, 0 fatal for reyneq
C:\D Drive\CML codes\Dynamic5a\Reynolds.F90(1489) : error S0155 : Module variables are not supported in acc routine - iqpo
C:\D Drive\CML codes\Dynamic5a\Reynolds.F90(1495) : error S0155 : Module variables are not supported in acc routine - t1
C:\D Drive\CML codes\Dynamic5a\Reynolds.F90(1500) : error S0155 : Module variables are not supported in acc routine - t2
C:\D Drive\CML codes\Dynamic5a\Reynolds.F90(1508) : error S0155 : Module variables are not supported in acc routine - t3
C:\D Drive\CML codes\Dynamic5a\Reynolds.F90(1509) : error S0155 : Module variables are not supported in acc routine - t4
C:\D Drive\CML codes\Dynamic5a\Reynolds.F90(1515) : error S0155 : Module variables are not supported in acc routine - d0
C:\D Drive\CML codes\Dynamic5a\Reynolds.F90(1516) : error S0155 : Module variables are not supported in acc routine - icoe
C:\D Drive\CML codes\Dynamic5a\Reynolds.F90(1519) : error S0155 : Module variables are not supported in acc routine - pir
C:\D Drive\CML codes\Dynamic5a\Reynolds.F90(1520) : error S0155 : Module variables are not supported in acc routine - gama
C:\D Drive\CML codes\Dynamic5a\Reynolds.F90(1521) : error S0155 : Module variables are not supported in acc routine - nter
C:\D Drive\CML codes\Dynamic5a\Reynolds.F90(1537) : error S0155 : Module variables are not supported in acc routine - pit
C:\D Drive\CML codes\Dynamic5a\Reynolds.F90(1583) : error S0155 : Module variables are not supported in acc routine - zdat
C:\D Drive\CML codes\Dynamic5a\Reynolds.F90(1583) : error S0155 : Module variables are not supported in acc routine - zdat
C:\D Drive\CML codes\Dynamic5a\Reynolds.F90(1585) : error S0155 : Module variables are not supported in acc routine - qndat
C:\D Drive\CML codes\Dynamic5a\Reynolds.F90(1585) : error S0155 : Module variables are not supported in acc routine - qndat
C:\D Drive\CML codes\Dynamic5a\Reynolds.F90(1586) : error S0155 : Module variables are not supported in acc routine - zdat
C:\D Drive\CML codes\Dynamic5a\Reynolds.F90(1587) : error S0155 : Module variables are not supported in acc routine - qndat
flow:
   1466, Generating acc routine seq
   1521, Loop is parallelizable
   1547, Loop carried scalar dependence for ff0 at line 1551
         Scalar last value needed after loop for ff0 at line 1562
         Loop carried scalar dependence for f1 at line 1557
         Scalar last value needed after loop for f1 at line 1563
         Loop carried scalar dependence for f2 at line 1559
         Scalar last value needed after loop for f2 at line 1564
  0 inform,   0 warnings,  17 severes, 0 fatal for flow
Roughness.F90
Stiff.F90
String.F90
Suspension.F90
UserDefGeom.F90
Util.F90
Dynamic5 build failed.
Build log was saved at "file://C:\D Drive\CML codes\Dynamic5a\x64\Release\BuildLog.htm"

========== Rebuild All: 0 succeeded, 1 failed, 0 skipped ==========

thanks,
Dolf

10 
what do you mean? please look at flow subroutine above and tell me if it's interface or not.

Since you are using computed gotos, I assumed this is old Fortran 77. It looks like “flows” in a module and thus has an implicit interface.

why would it be a problem?

Because we only just added support for them in OpenACC code.

how would I change it to case statements?

You would make each one of the sections jumped to by the different goto labels a separate case with “idisc” as your case expression.

  • Mat
11

what does it mean?

“C:\D Drive\CML codes\Dynamic5a\Reynolds.F90(1259) : error S0155 : Module variables are not supported in acc routine - t4”

I did what you told me to put !$acc routine flow sec in both places, but still get the error of: moving in or out from data region not allowed.

Please advice.

12

I have removed the calls to flow subroutine since it has module variables that are not supported by Acc. It gave the following error:

"C:\D Drive\CML codes\Dynamic5a\Reynolds.F90(1259) : error S0155 : Module variables are not supported in acc routine - t4"

Is there a way to remove the above error?
Now I have tridag subroutine which has no modules used in it. I have added what you told me to add in tridag (!$acc routine seq). And also added in reynolds subroutine (!$acc routine(tridag) seq) but still gives the following error:

C:\D Drive\CML codes\Dynamic5a\Reynolds.F90(166) : error S0155 : Invalid accelerator data region: branching into or out of region is not allowed 
reyneq:
    166, Invalid accelerator data region: branching into or out of region is not allowed

what shall I do to eliminate the issue?

Thanks,
Dolf

13

Is there a way to remove the above error?

Yes. In order to use module variables in a device routine, you need to add a “!$acc declare create(<variable_name>)” in the module where the variable is declared. This will create a global device reference which the routine can then access.


166, Invalid accelerator data region: branching into or out of region is not allowed

what shall I do to eliminate the issue?

This indicates that you have a compute region that can be jumped into or out of. In your case, most likely due to a “goto” or “return” statement.

To fix, the compute region (or just the “loop” construct) needs to have a single entry and exit.

  • Mat
14

Hi Mat,
It turned out that not the return statement, but the 50 label. there is a line that make you jump into the data region when condition satisfied.

So, where can I get all those details you been greatfuly explaining to me? I am reading the “PGI Accelerator Compilers OpenACC Getting Started Guide” but I don’t see your instructions there, is there another source that I need to look at?

thanks,
Dolf

15

Hi Dolf,

Support for module variables in OpenACC “routines” was just added recently so hasn’t propagated to our training. It’s also why the message still say it’s not supported (though we should be fixing this so it says to added a declare directive).

The single entry/single exit requirement is part of the OpenACC specification and I have had it in some of my all day training slide decks. Though it tends to get cut out of the smaller training and quick start guides since it’s implied as part of the definition for a structured block.

  • Mat
16

Hi Mat,

here is what my extended data region looks like: It compiles perfectly except when I use kernels (first two do loops) I get restriction due to dependencies.

!$acc data copyin(aj,bj,cj,dj,aw,ae,as,an,ar,ap,p,xref,yref), copyout(aj,bj,cj,dj,p), create(akd,akn) 
akd = 0.0
akn = 0.0
!$acc kernels 
!parallel loop gang 

do j=2,nym1
         jm1=j-1
         jp1=j+1
		 aj(im1)=0.d0 
         bj(im1)=0.d0 
         cj(im1)=0.d0 
         dj(im1)=0.d0 
         aj1=0.d0 
         bj1=0.d0 
         cj1=0.d0 
         dj1=0.d0 
!$acc loop vector 
          do i=2,nxm1
            im1=i-1
            ip1=i+1
            !aj(im1)=aw(im1,jm1)
            !bj(im1)=ap(im1,jm1)
            !cj(im1)=ae(im1,jm1)
            !dj(im1)=ar(im1,jm1)-as(im1,jm1)*p(i,jm1) - an(im1,jm1)*p(i,jp1)
			aj1=aw(im1,jm1)
            bj1=ap(im1,jm1)
            cj1=ae(im1,jm1)
            dj1=ar(im1,jm1)-as(im1,jm1)*p(i,jm1) - an(im1,jm1)*p(i,jp1)
            if(i.eq.2) then
              !dj(im1)=dj(im1)-aw(im1,jm1)*p(im1,j)
              !aj(im1)=0.d0
			  dj1=dj1-aw(im1,jm1)*p(im1,j)
              aj1=0.d0
            else if (i.eq.nxm1) then
              !dj(im1)=dj(im1)-ae(im1,jm1)*p(ip1,j)
              !cj(im1)=0.d0
			  dj1=dj1-ae(im1,jm1)*p(ip1,j)
              cj1=0.d0
            endif
            akd=akd+dabs(aj1*p(im1,j)+bj1*p(i,j) + cj1*p(ip1,j)-dj1)
            akn=akn+dabs(bj1*p(i,j))
          aj(im1)=aj1 
          bj(im1)=bj1 
          cj(im1)=cj1 
          dj(im1)=dj1
		  enddo	   
        enddo
!$acc end kernels

!$acc update host (akd,akn) async
write(*,*)akd,akn
	ak  = akd/akn
	!write(*,*)'idirect=',idirect
	write(*,*)'ak=',ak
	
	rakpre=ak
	kint=0

		aj = 0.d0
		bj = 0.d0
		cj = 0.d0
		dj = 0.d0
!$acc kernels
	do j=2,nym1
            jm1=j-1
            jp1=j+1
            ymyp=(yref(jp1)-yref(jm1))/2.d0
!
            do i=2,nxm1
              im1=i-1
              ip1=i+1
              xmxp=(xref(ip1)-xref(im1))/2.d0
!
              aj(im1)=aw(im1,jm1)
              bj(im1)=ap(im1,jm1)
              cj(im1)=ae(im1,jm1)
              dj(im1)=ar(im1,jm1)-as(im1,jm1)*p(i,jm1) - an(im1,jm1)*p(i,jp1)
!
              if(i.eq.2) then
                dj(im1)=dj(im1)-aw(im1,jm1)*p(im1,j)
                aj(im1)=0.d0
              else if (i.eq.nxm1) then
                dj(im1)=dj(im1)-ae(im1,jm1)*p(ip1,j)
                cj(im1)=0.d0
              endif
!
			enddo
            call tridag(nxm2,aj,bj,cj,dj,nxmax)
            do i=1,nxm2
              p(i+1,j)=dj(i)
			enddo
		enddo
!$acc end kernels
	
!$acc parallel loop gang 
      do i=2,nxm1 
          im1=i-1 
          ip1=i+1 
          xmxp=(xref(ip1)-xref(im1))/2.d0 
! 
          aj(im1)=0.d0 
          bj(im1)=0.d0 
          cj(im1)=0.d0 
          dj(im1)=0.d0 
          aj1=0.d0 
          bj1=0.d0 
          cj1=0.d0 
          dj1=0.d0 

!$acc loop vector 
          do j=2,nym1 
            jm1=j-1 
            jp1=j+1 
            ymyp=(yref(jp1)-yref(jm1))/2.d0 
! 
            aj1=aj1+aw(im1,jm1) 
            bj1=bj1+ap(im1,jm1) 
            if(j.ne.2) bj1=bj1+as(im1,jm1) 
            if(j.ne.nym1) bj1=bj1+an(im1,jm1) 
            cj1=cj1+ae(im1,jm1) 
            dj1=dj1+ar(im1,jm1)-aw(im1,jm1)*p(im1,j)    & 
                    -ae(im1,jm1)*p(ip1,j)-as(im1,jm1)*p(i,jm1)  & 
                    -an(im1,jm1)*p(i,jp1)-ap(im1,jm1)*p(i  ,j) 
! 
          enddo 
          aj(im1)=aj1 
          bj(im1)=bj1 
          cj(im1)=cj1 
          dj(im1)=dj1 
        enddo 
!$acc end parallel loop 
!$acc end data

compiler output:

reyneq:
    166, Generating copyout(aj(:),bj(:),cj(:),dj(:))
         Generating copyin(aw(:,:),ae(:,:),as(:,:),an(:,:),ar(:,:),ap(:,:))
         Generating copyout(p(:,:))
         Generating copyin(xref(:),yref(:))
         Generating create(akd,akn)
    172, Complex loop carried dependence of aj,bj,cj,dj prevents parallelization
         Parallelization would require privatization of array dj(:nxm1-1),dj(:),cj(:nxm1-1),cj(:),bj(:nxm1-1),bj(:),aj(:nxm1-1),aj(:)
         Accelerator kernel generated
         Generating Tesla code
        184, !$acc loop vector(128) ! threadidx%x
        206, Sum reduction generated for akd
        207, Sum reduction generated for akn
    184, Loop is parallelizable
    235, Generating update host(akn,akd)
    303, Generating copy(nxmax,nxm2)
    304, Loop carried dependence due to exposed use of aj(:),bj(:),cj(:) prevents parallelization
         Loop carried dependence of p prevents parallelization
         Loop carried dependence due to exposed use of dj(:) prevents parallelization
         Loop carried backward dependence of p prevents vectorization
         Accelerator kernel generated
         Generating Tesla code
        309, !$acc loop vector(128) ! threadidx%x
        329, !$acc loop vector(128) ! threadidx%x
    309, Loop is parallelizable
    329, Loop is parallelizable
    349, Accelerator kernel generated
         Generating Tesla code
        350, !$acc loop gang ! blockidx%x
        365, !$acc loop vector(128) ! threadidx%x
        370, Sum reduction generated for aj1
        374, Sum reduction generated for cj1
        375, Sum reduction generated for dj1
    365, Scalar last value needed after loop for bj1 at line 381
         Accelerator restriction: scalar variable live-out from loop: bj1
Roughness.F90
Stiff.F90
String.F90
Suspension.F90
UserDefGeom.F90
Util.F90
tridag:
    229, Generating acc routine seq
    242, Loop is parallelizable
    248, Loop is parallelizable
Linking...
Dynamic5 build succeeded.

Build log was saved at "file://C:\D Drive\CML codes\Dynamic5a\x64\Release\BuildLog.htm"

========== Rebuild All: 1 succeeded, 0 failed, 0 skipped ==========

what do I need to make accelerated kernels? also, I don’t get correct akd,akn. what could be wrong?

thanks,
Dolf

17

Hi Dolf,

The code doesn’t look correct to me. Does this code work without OpenACC?

In the first two loops you use the index variable “im1” for aj, bj, cj, and dj. Is this a mistake and it should this be “jm1”?

For example, this bit “im1” isn’t initialized:

do j=2,nym1 
         jm1=j-1 
         jp1=j+1 
       aj(im1)=0.d0 
         bj(im1)=0.d0 
         cj(im1)=0.d0 
         dj(im1)=0.d0

Though assuming you really want “jm1”, the inner loop assignment would then be wrong. Should the assignment to these arrays be done after the “I” loop?

            akd=akd+dabs(aj1*p(im1,j)+bj1*p(i,j) + cj1*p(ip1,j)-dj1) 
            akn=akn+dabs(bj1*p(i,j)) 
>> move enddo here?
          aj(im1)=aj1 
          bj(im1)=bj1 
          cj(im1)=cj1 
          dj(im1)=dj1 
>>        enddo       
        enddo
  • Mat
18

Hi Mat,

aj(im1)=0.d0 
bj(im1)=0.d0 
cj(im1)=0.d0 
dj(im1)=0.d0 
aj1=0.d0 
bj1=0.d0 
cj1=0.d0 
dj1=0.d0

you are right, those matrices I put them there. I thought it’s a good idea to initialize. you could remove them. if you remove them, still the code does not work and the akn,akd will equal to zero with acc directives. Please advice.

thanks,
Dolf

19

Hi Dolf,

I noticed that you have these variables in a create clause: “create(akd,akn)”. This causes the variables to not copied back to the host, hence the values you printing are what the host’s original value is. The fix is to add an update directive before you print.

“!$acc update host (akd,akn)”

  • Mat
20

Hi Mat,

I did !$acc update host (akd,akn) right before I write akd,akn but still they read 0.0. It is very confusing and not making allot of sense.

Dolf