On Nov 3, 2012, at 8:20 PM, Mohammad Mirzadeh wrote: > Hum ... That did not help. I found this -threadcomm_affinities > 0,1,2,3,4,5,6,7 but that also did nothing. Is that option any relevant? This option currently only works with pthreads. > > Another question: the linux box I'm testing on has 2 quad-cores (8 cores/2 > sockets). If I run the code with mpirun -np 8, I get about 3X which makes > sense to me. However, If I run with either pthread (which seems to use all > cores) or openmp (which always defaults to 1 no matter what) As I said before you have to set the core affinity for OpenMP through environment variables. > I get the same performance as serial. i) Which example are you running? Please send output of -log_summary. ii) Only the vector and a few matrix operations are threaded currently. There are no threaded preconditioners yet. > Does this mean there is something messed up with the hardware and/or how > mpi/openmp/pthread is set up?
Shri > > > On Fri, Nov 2, 2012 at 8:24 PM, Shri <abhyshr at mcs.anl.gov> wrote: > > On Nov 2, 2012, at 9:54 PM, Mohammad Mirzadeh wrote: > > > Hi, > > > > To use the new thread model in PETSc, does it suffice to run the code with > > the following? > > > > -threadcomm_type <openmp/pthread> -threadcomm_nthreads <#> > > > > When I run the code with openmp, only 1 processor/core is active (looking > > at top). When using pthread, all cores are active. Am I missing something? > OpenMP defaults to binding all threads to a single core if the cpu affinity > is not specified explicitly. If you > are using GNU OpenMP then you can bind the threads to specific cores using > the environment variable GOMP_CPU_AFFINITY > http://gcc.gnu.org/onlinedocs/libgomp/GOMP_005fCPU_005fAFFINITY.html > If you are some other OpenMP implementation then check its manual to see how > to set cpu affinity. > > Shri > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20121103/88ce0677/attachment.html>
