Hi,
I spent some time talking to jakub who runs the gcc forum and he disagrees with
you. A digest follows of our exchanges and a link to the entire thread.
A related problem may be that the test for pthread_setaffinity_np fails in
CMake. See my second post from yesterday.
Ralph
Initially, I sent email to [EMAIL PROTECTED] The entire thread may be found at:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37586
After a number of emails jakub responded:
*************************************************************************
(A strace -f -e sched_getaffinity dump by me yielded the following:
jakub responded:
sched_getaffinity(3502, 128, { ff, 0, 0, 0 }) = 32
....
sched_getaffinity(3502, 128, { 1, 0, 0, 0 }) = 32
...
sched_getaffinity(3502, 128, { 1, 0, 0, 0 }) = 32
Shows that the process originally was bound to any of the 8 CPUs (mask 0xff),
but after a while it got confined only to the first CPU. The question is what
has done that. You can look for sched_setaffinity syscall in the strace dump,
then either from the surrounding syscalls or under debugger find out where
sched_setaffinity or pthread_setaffinity_np functions have been called from
or if the program invokes the syscall directly, without calling a
libc/libpthread function.
****************************************************************************
I responded:
Hi Jakub,
I did as you asked and get:
sched_setaffinity(24094, 128, { 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0 }) = 0
Its buried in other "startup" code:
..............................
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
sched_setaffinity(24094, 128, { 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0 }) = 0
INFO> navigation mode set to umbra
Warning: font file "fonts/arial.ttf" not found.
Setting savConfigCB to '::guiWrapper saveConfig'
sLoadFile filename:/home/vision_data/geometry_objects/test.cdf
fileType: lineRowCnt=-1 lineColCnt=-1
std::string UmbModCDFDataSet::LoadFile(const s......
...................................
I suppose that this means that something in Tcl, OpenScenegraph, umbra,
my own rwm is setting the following software to run on only one
processor. I ran a strace -f to get a full "dump" and found that it
occurs between 2 "open(library)" calls. I backtracked to OpenSceneGraph
to find one possibility:
[EMAIL PROTECTED] src]$ pwd
/usr/local/src/OpenSceneGraph-2.4.0/src
[EMAIL PROTECTED] src]$ find . -exec grep -n -H sched_setaffinity {} \;
./OpenThreads/pthreads/CMakeLists.txt:73: sched_setaffinity( 0,
sizeof(cpumask), &cpumask );
./OpenThreads/pthreads/CMakeLists.txt:83: sched_setaffinity( 0, &cpumask );
./OpenThreads/pthreads/PThread.c++:135: sched_setaffinity( 0,
sizeof(cpumask), &cpumask );
./OpenThreads/pthreads/PThread.c++:137: sched_setaffinity( 0,
&cpumask );
./OpenThreads/pthreads/PThread.c++:549: sched_setaffinity( 0,
sizeof(cpumask), &cpumask );
./OpenThreads/pthreads/PThread.c++:551: sched_setaffinity( 0,
&cpumask );
./OpenThreads/pthreads/PThread.c++:984: sched_setaffinity( 0,
sizeof(cpumask), &cpumask );
./OpenThreads/pthreads/PThread.c++:986: sched_setaffinity( 0,
&cpumask );
./OpenThreads/pthreads/GNUmakefile:43:ifeq
($(COMPILE_USING_TWO_PARAM_sched_setaffinity),yes)
./OpenThreads/pthreads/GNUmakefile:44:DEF +=
-DCOMPILE_USING_TWO_PARAM_sched_setaffinity
[EMAIL PROTECTED] src]$
This looks like a possibility for the source of my problem or not?
Can I make my own call to sched_setaffinity? There is, of course,
always the possibility of causing problems.
Ralph
***************************************************************************
jakub responded:
-
------ Comment #9 from jakub at gcc dot gnu dot org 2008-10-13 17:52 -------
Yes, that certainly is the source of your problems. You could call
sched_setaffinity or pthread_sched_setaffinity in your program before entering
an OpenMP region, guess you should also find out why does that library confine
the thread to just one CPU.
Anyway, closing this, as it clearly is not a GCC/libgomp bug.
***************************************************************************
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