Hi,
I will try to be much more concise! :-)
The problem appears to be that
SetProcessorAffinityOfCurrentThread(unsigned int cpunum) is always being
called with a cpunum value of zero. More information follows.
I am trying to use OpenMP with an application that uses OpenScenGraph.
When OpenMP runs it says that there is only 1 CPU available on an 8
processor PC.
After numerous exchanges with jakub (thread may be found at
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37586), it appears that a
call to sched_setaffinity, or its "wrapper" pthread_setaffinity_np, is
setting the number of processors available to 1 on my PC.
After a fair amount of looking around, I dug deep into OpenSceneGraph
software and found 3 instances in
OpenSceneGraph-2.4.0/src/OpenThreads/pthreads/ PThread.c++ where calls
of this sort are being made. I put printouts in those places to check
on what is going on. I found that only one call to
pthread_setaffinity_np was being run in
SetProcessorAffinityOfCurrentThread(unsigned int cpunum) -- see below.
A short code fragment from SetProcessorAffinityOfCurrentThread follows
which shows my printout.
#if defined(HAVE_PTHREAD_SETAFFINITY_NP)
std::cout << "SetProcessorAffinityOfCurrentThread cpunum=" <<
cpunum << " sizeof(cpumask)=" << sizeof(cpumask) << std::endl;
pthread_setaffinity_np( pthread_self(), sizeof(cpumask), &cpumask);
#elif defined(HAVE_THREE_PARAM_SCHED_SETAFFINITY)
sched_setaffinity( 0, sizeof(cpumask), &cpumask );
#elif defined(HAVE_TWO_PARAM_SCHED_SETAFFINITY)
sched_setaffinity( 0, &cpumask );
#endif
#endif
If I use strace -f -e sched_setaffinity to watch what is happening with
sched_setaffinity I see (partial output listing follows):
NOTE: usg::Scene using usg default data file path list
path =
.:/usr/local/share/OpenSceneGraph/data:/usr/local/share/OpenSceneGraph/data/Env:/usr/local/share/OpenSceneGraph/data/fonts:/usr/local/share/OpenSceneGraph/data/Images:/usr/share/OpenSceneGraph/data:/usr/share/OpenSceneGraph/data/Env:/usr/share/OpenSceneGraph/data/fonts:/usr/share/OpenSceneGraph/data/Images
camera number: 0
SetProcessorAffinityOfCurrentThread cpunum=0 sizeof(cpumask)=128
sched_setaffinity(16718, 128, { 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0 }) = 0
INFO> navigation mode set to umbra
which seems to imply that the call pthread_setaffinity_np with zero
processors is causing a problem.
I looked for calls to this function and found the following which
explains why cpunum is zero!
../src/osgViewer/ViewerBase.cpp:137:
OpenThreads::SetProcessorAffinityOfCurrentThread(0);
../src/osgViewer/ViewerBase.cpp:452:
OpenThreads::SetProcessorAffinityOfCurrentThread(0);
What do you, particularly Robert, think? (More information concerning
my PC is available.) How can we fix this? I am quite happy to run some
experiments to figure this out.
Ralph
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