Faluire in execute (call to cuStreamSynchronize returned error 700: Illegal address during kernel execution)

Accelerated Computing HPC Compilers nvc, nvc++ and nvfortran
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1

Hi,

I am trying to accelerate only one function from the code I am using the directive.

#pragma acc data create [some arrays]
#pragma acc kernels

after compilation, the result is as below:

1896, Generating implicit copyin(this[:]) [if not already present]
Generating create(u_field.vector[:local_size],v_field.vector[:local_size],w_field.vector[:local_size],delta_z_field.vector[:local_size],kappa_field.vector[:local_size],T_field.vector[:local_size],delta_x_field.vector[:local_size],delta_y_field.vector[:local_size],rhoE_vis_flux.vector[:local_size],rhou_vis_flux.vector[:local_size],rhov_vis_flux.vector[:local_size],mu_field.vector[:local_size]) [if not already present]

then fail to execute with error (call to cuStreamSynchronize returned error 700: Illegal address during kernel execution)

Why it’s generating (Generating implicit copyin(this[:]) [if not already present]) and I didn’t specify this copy and the function has no pointers. how to turn it off?

Best,

2

I’m presuming you’re doing this within a class method. In this case, classes have a hidden ‘this’ pointer for which the class’ members are accessed. Hence it needs to be copied to the device as well.

If you can provide more information, and preferably a minimal reproducing example, I can provide better assistance on finding the cause of the error.

I do have some examples for using OpenACC data management within classes that may be useful. See the “accList” examples at: https://github.com/rmfarber/ParallelProgrammingWithOpenACC/tree/master/Chapter05

-Mat

3

Thanks for your last feedback I am accelerating the below function part of a solver, It’s hard to extract it to a minimal example, but I analyzed every part of it the problem is with the last part of it the fluxes rhou_vis_flux[I1D(i,j,k)], rhov_vis_flux[I1D(i,j,k)], rhow_vis_flux[I1D(i,j,k)] and rhoE_vis_flux[I1D(i,j,k)].

void FlowSolverRHEA::calculateViscousFluxes() {

/// Second-order central finite differences for derivatives:
/// P. Moin.
/// Fundamentals of engineering numerical analysis.
/// Cambridge University Press, 2010.

/// Inner points: rho_vis_flux, rhou_vis_flux, rhov_vis_flux, rhow_vis_flux and rhoE_vis_flux
const int local_size_x = _lNx_;
const int local_size_y = _lNy_;
const int local_size_z = _lNz_;
const int local_size   = local_size_x*local_size_y*local_size_z;

double delta_x, delta_y, delta_z;
double d_u_x, d_u_y, d_u_z, d_v_x, d_v_y, d_v_z, d_w_x, d_w_y, d_w_z;
double d_T_x, d_T_y, d_T_z;
double d_mu_x, d_mu_y, d_mu_z, d_kappa_x, d_kappa_y, d_kappa_z;
double div_uvw, tau_xx, tau_xy, tau_xz, tau_yy, tau_yz, tau_zz;
double div_tau_x, div_tau_y, div_tau_z;
double div_q, div_uvw_tau;

int inix = topo->iter_common[_INNER_][_INIX_];
int iniy = topo->iter_common[_INNER_][_INIY_];
int iniz = topo->iter_common[_INNER_][_INIZ_];
int endx = topo->iter_common[_INNER_][_ENDX_];
int endy = topo->iter_common[_INNER_][_ENDY_];
int endz = topo->iter_common[_INNER_][_ENDZ_];

#pragma acc kernels
for(int i = inix; i <= endx; i++) {
for(int j = iniy; j <= endy; j++) {
for(int k = iniz; k <= endz; k++) {
/// Geometric stuff
delta_x = delta_x_field[I1D(i,j,k)];
delta_y = delta_y_field[I1D(i,j,k)];
delta_z = delta_z_field[I1D(i,j,k)];
/// Velocity derivatives
d_u_x = ( u_field[I1D(i+1,j,k)] - u_field[I1D(i-1,j,k)] )/( 2.0delta_x );
d_u_y = ( u_field[I1D(i,j+1,k)] - u_field[I1D(i,j-1,k)] )/( 2.0delta_y );
d_u_z = ( u_field[I1D(i,j,k+1)] - u_field[I1D(i,j,k-1)] )/( 2.0delta_z );
d_v_x = ( v_field[I1D(i+1,j,k)] - v_field[I1D(i-1,j,k)] )/( 2.0delta_x );
d_v_y = ( v_field[I1D(i,j+1,k)] - v_field[I1D(i,j-1,k)] )/( 2.0delta_y );
d_v_z = ( v_field[I1D(i,j,k+1)] - v_field[I1D(i,j,k-1)] )/( 2.0delta_z );
d_w_x = ( w_field[I1D(i+1,j,k)] - w_field[I1D(i-1,j,k)] )/( 2.0delta_x );
d_w_y = ( w_field[I1D(i,j+1,k)] - w_field[I1D(i,j-1,k)] )/( 2.0delta_y );
d_w_z = ( w_field[I1D(i,j,k+1)] - w_field[I1D(i,j,k-1)] )/( 2.0delta_z );
/// Temperature derivatives
d_T_x = ( T_field[I1D(i+1,j,k)] - T_field[I1D(i-1,j,k)] )/( 2.0delta_x );
d_T_y = ( T_field[I1D(i,j+1,k)] - T_field[I1D(i,j-1,k)] )/( 2.0delta_y );
d_T_z = ( T_field[I1D(i,j,k+1)] - T_field[I1D(i,j,k-1)] )/( 2.0delta_z );
/// Transport coefficients derivatives
d_mu_x = ( mu_field[I1D(i+1,j,k)] - mu_field[I1D(i-1,j,k)] )/( 2.0delta_x );
d_mu_y = ( mu_field[I1D(i,j+1,k)] - mu_field[I1D(i,j-1,k)] )/( 2.0delta_y );
d_mu_z = ( mu_field[I1D(i,j,k+1)] - mu_field[I1D(i,j,k-1)] )/( 2.0delta_z );
d_kappa_x = ( kappa_field[I1D(i+1,j,k)] - kappa_field[I1D(i-1,j,k)] )/( 2.0delta_x );
d_kappa_y = ( kappa_field[I1D(i,j+1,k)] - kappa_field[I1D(i,j-1,k)] )/( 2.0delta_y );
d_kappa_z = ( kappa_field[I1D(i,j,k+1)] - kappa_field[I1D(i,j,k-1)] )/( 2.0delta_z );
/// Divergence of velocity
div_uvw = d_u_x + d_v_y + d_w_z;
/// Viscous stresses ( symmetric tensor )
tau_xx = 2.0mu_field[I1D(i,j,k)]( d_u_x - ( div_uvw/3.0 ) );
tau_xy = mu_field[I1D(i,j,k)]( d_u_y + d_v_x );
tau_xz = mu_field[I1D(i,j,k)]( d_u_z + d_w_x );
tau_yy = 2.0mu_field[I1D(i,j,k)]( d_v_y - ( div_uvw/3.0 ) );
tau_yz = mu_field[I1D(i,j,k)]( d_v_z + d_w_y );
tau_zz = 2.0mu_field[I1D(i,j,k)]*( d_w_z - ( div_uvw/3.0 ) );

/// Divergence of viscous stresses
div_tau_x = mu_field[I1D(i,j,k)]( ( 1.00/delta_x )( ( u_field[I1D(i+1,j,k)] - u_field[I1D(i,j,k)] )/( mesh->x[i+1] - mesh->x[i] )
- ( u_field[I1D(i,j,k)] - u_field[I1D(i-1,j,k)] )/( mesh->x[i] - mesh->x[i-1] ) )
+ ( 1.00/delta_y )( ( u_field[I1D(i,j+1,k)] - u_field[I1D(i,j,k)] )/( mesh->y[j+1] - mesh->y[j] )
- ( u_field[I1D(i,j,k)] - u_field[I1D(i,j-1,k)] )/( mesh->y[j] - mesh->y[j-1] ) )
+ ( 1.00/delta_z )( ( u_field[I1D(i,j,k+1)] - u_field[I1D(i,j,k)] )/( mesh->z[k+1] - mesh->z[k] )
- ( u_field[I1D(i,j,k)] - u_field[I1D(i,j,k-1)] )/( mesh->z[k] - mesh->z[k-1] ) ) )
+ ( 1.0/3.0 )mu_field[I1D(i,j,k)]( ( 1.00/delta_x )( ( u_field[I1D(i+1,j,k)] - u_field[I1D(i,j,k)] )/( mesh->x[i+1] - mesh->x[i] )
- ( u_field[I1D(i,j,k)] - u_field[I1D(i-1,j,k)] )/( mesh->x[i] - mesh->x[i-1] ) )
+ ( 0.25/delta_x )( ( v_field[I1D(i+1,j+1,k)] - v_field[I1D(i+1,j-1,k)] )/delta_y
- ( v_field[I1D(i-1,j+1,k)] - v_field[I1D(i-1,j-1,k)] )/delta_y )
+ ( 0.25/delta_x )( ( w_field[I1D(i+1,j,k+1)] - w_field[I1D(i+1,j,k-1)] )/delta_z
- ( w_field[I1D(i-1,j,k+1)] - w_field[I1D(i-1,j,k-1)] )/delta_z ) )
+ d_mu_xtau_xx + d_mu_ytau_xy + d_mu_ztau_xz;
div_tau_y = mu_field[I1D(i,j,k)]( ( 1.00/delta_x )( ( v_field[I1D(i+1,j,k)] - v_field[I1D(i,j,k)] )/( mesh->x[i+1] - mesh->x[i] )
- ( v_field[I1D(i,j,k)] - v_field[I1D(i-1,j,k)] )/( mesh->x[i] - mesh->x[i-1] ) )
+ ( 1.00/delta_y )( ( v_field[I1D(i,j+1,k)] - v_field[I1D(i,j,k)] )/( mesh->y[j+1] - mesh->y[j] )
- ( v_field[I1D(i,j,k)] - v_field[I1D(i,j-1,k)] )/( mesh->y[j] - mesh->y[j-1] ) )
+ ( 1.00/delta_z )( ( v_field[I1D(i,j,k+1)] - v_field[I1D(i,j,k)] )/( mesh->z[k+1] - mesh->z[k] )
- ( v_field[I1D(i,j,k)] - v_field[I1D(i,j,k-1)] )/( mesh->z[k] - mesh->z[k-1] ) ) )
+ ( 1.0/3.0 )mu_field[I1D(i,j,k)]( ( 0.25/delta_y )( ( u_field[I1D(i+1,j+1,k)] - u_field[I1D(i-1,j+1,k)] )/delta_x
- ( u_field[I1D(i+1,j-1,k)] - u_field[I1D(i-1,j-1,k)] )/delta_x )
+ ( 1.00/delta_y )( ( v_field[I1D(i,j+1,k)] - v_field[I1D(i,j,k)] )/( mesh->y[j+1] - mesh->y[j] )
- ( v_field[I1D(i,j,k)] - v_field[I1D(i,j-1,k)] )/( mesh->y[j] - mesh->y[j-1] ) )
+ ( 0.25/delta_y )( ( w_field[I1D(i,j+1,k+1)] - w_field[I1D(i,j+1,k-1)] )/delta_z
- ( w_field[I1D(i,j-1,k+1)] - w_field[I1D(i,j-1,k-1)] )/delta_z ) )
+ d_mu_xtau_xy + d_mu_ytau_yy + d_mu_ztau_yz;
div_tau_z = mu_field[I1D(i,j,k)]( ( 1.00/delta_x )( ( w_field[I1D(i+1,j,k)] - w_field[I1D(i,j,k)] )/( mesh->x[i+1] - mesh->x[i] )
- ( w_field[I1D(i,j,k)] - w_field[I1D(i-1,j,k)] )/( mesh->x[i] - mesh->x[i-1] ) )
+ ( 1.00/delta_y )( ( w_field[I1D(i,j+1,k)] - w_field[I1D(i,j,k)] )/( mesh->y[j+1] - mesh->y[j] )
- ( w_field[I1D(i,j,k)] - w_field[I1D(i,j-1,k)] )/( mesh->y[j] - mesh->y[j-1] ) )
+ ( 1.00/delta_z )( ( w_field[I1D(i,j,k+1)] - w_field[I1D(i,j,k)] )/( mesh->z[k+1] - mesh->z[k] )
- ( w_field[I1D(i,j,k)] - w_field[I1D(i,j,k-1)] )/( mesh->z[k] - mesh->z[k-1] ) ) )
+ ( 1.0/3.0 )mu_field[I1D(i,j,k)]( ( 0.25/delta_z )( ( u_field[I1D(i+1,j,k+1)] - u_field[I1D(i-1,j,k+1)] )/delta_x
- ( u_field[I1D(i+1,j,k-1)] - u_field[I1D(i-1,j,k-1)] )/delta_x )
+ ( 0.25/delta_z )( ( v_field[I1D(i,j+1,k+1)] - v_field[I1D(i,j-1,k+1)] )/delta_y
- ( v_field[I1D(i,j+1,k-1)] - v_field[I1D(i,j-1,k-1)] )/delta_y )
+ ( 1.00/delta_z )( ( w_field[I1D(i,j,k+1)] - w_field[I1D(i,j,k)] )/( mesh->z[k+1] - mesh->z[k] )
- ( w_field[I1D(i,j,k)] - w_field[I1D(i,j,k-1)] )/( mesh->z[k] - mesh->z[k-1] ) ) )
+ d_mu_xtau_xz + d_mu_ytau_yz + d_mu_ztau_zz;
/// Fourier term
div_q = ( -1.0 )kappa_field[I1D(i,j,k)]( ( 1.0/delta_x )( ( T_field[I1D(i+1,j,k)] - T_field[I1D(i,j,k)] )/( mesh->x[i+1] - mesh->x[i] )
- ( T_field[I1D(i,j,k)] - T_field[I1D(i-1,j,k)] )/( mesh->x[i] - mesh->x[i-1] ) )
+ ( 1.0/delta_y )( ( T_field[I1D(i,j+1,k)] - T_field[I1D(i,j,k)] )/( mesh->y[j+1] - mesh->y[j] )
- ( T_field[I1D(i,j,k)] - T_field[I1D(i,j-1,k)] )/( mesh->y[j] - mesh->y[j-1] ) )
+ ( 1.0/delta_z )( ( T_field[I1D(i,j,k+1)] - T_field[I1D(i,j,k)] )/( mesh->z[k+1] - mesh->z[k] )
- ( T_field[I1D(i,j,k)] - T_field[I1D(i,j,k-1)] )/( mesh->z[k] - mesh->z[k-1] ) ) )
- d_kappa_xd_T_x - d_kappa_yd_T_y - d_kappa_zd_T_z;
/// Work of viscous stresses
div_uvw_tau = u_field[I1D(i,j,k)]div_tau_x + v_field[I1D(i,j,k)]div_tau_y + w_field[I1D(i,j,k)]div_tau_z
+ tau_xxd_u_x + tau_xyd_u_y + tau_xzd_u_z
+ tau_xyd_v_x + tau_yyd_v_y + tau_yzd_v_z
+ tau_xzd_w_x + tau_yzd_w_y + tau_zzd_w_z;

            /// Viscous fluxes
            rhou_vis_flux[I1D(i,j,k)] = div_tau_x;
            rhov_vis_flux[I1D(i,j,k)] = div_tau_y;
            rhow_vis_flux[I1D(i,j,k)] = div_tau_z;
            rhoE_vis_flux[I1D(i,j,k)] = ( -1.0 )*div_q + div_uvw_tau;
        }
    }
}
/// Update halo values
//rhou_vis_flux.update();
//rhov_vis_flux.update();
//rhow_vis_flux.update();
//rhoE_vis_flux.update();

};

All the arrays in this function are arrays of objects and all of them can be copied in and out without problems and the function runs properly except for the fluxes at the end as I mentioned in the beginning when I uncomment them and run I got below message

FlowSolverRHEA::calculateViscousFluxes():
1927, Generating implicit copyin(this[:]) [if not already present]
1934, Complex loop carried dependence of lNy,lNz,mesh,mesh->x,mesh->x->,mesh->z,mesh->z->,mesh->y-> prevents parallelization
Accelerator serial kernel generated
Generating Tesla code
1934, #pragma acc loop seq
1935, #pragma acc loop seq
1936, #pragma acc loop seq
1935, Complex loop carried dependence of lNz,lNy,mesh->x->,mesh->x,mesh->z->,mesh->y->,mesh->y,mesh->z prevents parallelization
1936, Complex loop carried dependence of lNz,lNy,mesh->x->,mesh->x,mesh->z->,mesh->y->,mesh->y,mesh->z prevents parallelization

Then when executing I receive below error:

RHEA (v1.1.0): START SIMULATION
Time iteration 10: time = 6.42379e-05 [s], time-step = 6.42238e-06 [s], wall-clock time = 4.25751e-03 [h]
Failing in Thread:1
call to cuStreamSynchronize returned error 700: Illegal address during kernel execution

Do you have an Idea why this could be happening only with these arrays ( rhou_vis_flux[I1D(i,j,k)], rhov_vis_flux[I1D(i,j,k)], rhow_vis_flux[I1D(i,j,k)] and rhoE_vis_flux[I1D(i,j,k)]) noting that all the other arrays in the function are the same but only these that generate this problem ?

Thanks
Ahmed

4

Hi Ahmed,

Can you post how you are creating and copying the device arrays (i.e. what are you’re “enter data” directives)? Also, are you explicitly creating the “this” pointer?

You might want to try using CUDA Unified Memory (i.e. add “-gpu=managed”). All allocated data will then be managed by the CUDA driver so you don’t need to worry about doing a deep copy of the class data.

Also, the code isn’t getting parallelized. You’re using the “kernels” construct where the compiler must prove independence, but given the potential for pointer aliasing, it’s finding dependencies which prevent parallelization. Use the “independent” clause to assert that the loop is independent or use “parallel” instead where “independent” is the default. I’d also suggest using “collapse(3)” so all the loops are parallelized.

Examples:

#pragma acc kernels loop collapse(3) independent
for(int i = inix; i <= endx; i++) {
for(int j = iniy; j <= endy; j++) {
for(int k = iniz; k <= endz; k++) {

or

#pragma acc parallel loop collapse(3)
for(int i = inix; i <= endx; i++) {
for(int j = iniy; j <= endy; j++) {
for(int k = iniz; k <= endz; k++) {

-Mat

5

I am using the below pragmas for copying in and creating

#pragma acc enter data copyin (u_field.vector[0:local_size], v_field.vector[0:local_size],w_field.vector[0:local_size],T_field.vector[0:local_size],kappa_field.vector[0:local_size], mu_field.vector[0:local_size],delta_x_field.vector[0:local_size], delta_y_field.vector[0:local_size], delta_z_field.vector[0:local_size])
#pragma acc enter data create (rhou_vis_flux.vector[0:local_size], rhov_vis_flux.vector[0:local_size], rhow_vis_flux.vector[0:local_size], rhoE_vis_flux.vector[0:local_size])
#pragma acc parallel loop collapse (3)
for(int i = inix; i <= endx; i++) {
for(int j = iniy; j <= endy; j++) {
for(int k = iniz; k <= endz; k++) {

I am not creating “this” pointer it’s creating copy automatically when I add the pragmas for example the collapse I don’t know why?

I already used managed memory and I have a version that is working but I need to have a version using manual memory movement.

I used the previously suggested pragmas over the loops and the same result when executing

FlowSolverRHEA::calculateViscousFluxes():
1927, Generating Tesla code
1934, #pragma acc loop gang, vector(128) collapse(3) /* blockIdx.x threadIdx.x /
1935, / blockIdx.x threadIdx.x collapsed /
1936, / blockIdx.x threadIdx.x collapsed */
1927, Generating implicit copyin(this[:]) [if not already present]

RHEA (v1.1.0): START SIMULATION
Time iteration 10: time = 6.42379e-05 [s], time-step = 6.42238e-06 [s], wall-clock time = 4.25440e-03 [h]
Failing in Thread:1
call to cuStreamSynchronize returned error 700: Illegal address during kernel execution

I don’t know what I am doing wrong?

Best,
Ahmed

6

You don’t know why the this pointer is implicitly copied or why there’s a this pointer at all?

The instantiated object of a class is implicitly accessed via that object’s this pointer. i.e. although you only need to write “array[idx]”, in actuality it’s being accessed as “this->array[dix]”. Hence the this pointer needs to be on the device as well.

The this pointer should be created on the device prior to creating any of it’s data members. This way the compiler can implicitly “attach” them. An “attach” basically sets the device pointer address to the data members in the device copy of the ‘this’ object. You can manually attach via the “attach” clause, or the “acc_attach” API routine, but the compiler can implicitly do this if the parent object is created on the device before the children.

When the compiler has to do an implicit copy of the this pointer, it’s only doing a shallow copy, so will contain the host addresses of the data members. Hence when you access a data member “this->array[idx]”,. the host address is used and the illegal address error occurs.

While not the best way to do this, but the simple fix here is to simply add “this” to your copyin clause before the data members.

#pragma acc enter data copyin (this, u_field.vector[0:local_size],

The better method is to add the “enter data” to the constructor or initialization routines, as well as adding methods to handle the “updates” between the device and host. This is how I do this in the accList example I posted above.

For more details on attach and deep copy please see: Deep Copy Support in OpenACC | PGI

Though note that Michael is using classes without methods (basically C style structs) so copying the objects directly. Your code is accessing the data within a method and why we need work with the this pointer.

Hope this helps,
Mat

7

My note about the lack of parallelization was not to imply that this would fix the illegal address error. I was just pointing it out since the code would be very slow once you do fix the error.