Are cutil timers thread-safe?

Accelerated Computing CUDA CUDA Programming and Performance
1

I added cutil timers to my multi-gpu code - each GPU thread creates a couple timers, uses them independently, then destroys them. I occasionally get a segmentation fault when starting or stopping the timer:

Core was generated by `./test'.

Program terminated with signal 11, Segmentation fault.

Cannot access memory at address 0xb7f14000

#0  0x0816947e in StopWatchLinux::getDiffTime (this=0x0) at /usr/local/cudasdk/common/inc/stopwatch_linux.h:178

178       return  (float) (1000.0 * ( t_time.tv_sec - start_time.tv_sec)

(gdb) bt

#0  0x0816947e in StopWatchLinux::getDiffTime (this=0x0) at /usr/local/cudasdk/common/inc/stopwatch_linux.h:178

#1  0x08169439 in StopWatchLinux::stop (this=0x0) at /usr/local/cudasdk/common/inc/stopwatch_linux.h:117

#2  0x0816941f in StopWatchBase<StopWatchLinux>::stop (this=0x0) at /usr/local/cudasdk/common/inc/stopwatch_base.inl:63

#3  0x081664e0 in cutStopTimer (name=39) at src/cutil.cpp:1406

#4  0x080a97a8 in _Z10jachthreadPv (voidparams=0x8af6078) at host_multigpu.cu:1077

#5  0x001703cc in ?? ()

#6  0x08af6078 in ?? ()

#7  0x0237aba0 in ?? ()

#8  0x0237aba0 in ?? ()

#9  0x0237aba0 in ?? ()

#10 0x0237a3e0 in ?? ()

#11 0x00000000 in ?? ()

This would seem to indicate the “StopWatchLinux” object has been destroyed, presumably from a call to cutDeleteTimer in a different thread. Are cutil timers thread safe?

2

They’re not thread safe… CUtil uses a global pool of stopwatches which is not mutex protected.

3

Thanks for the response, wumpus. Looks like I’ll be writing up a thread-safe timer.