[FFmpeg-devel] [PATCH] Runtime detection for the number of processors/cores
François Revol
revol
Wed May 21 15:54:15 CEST 2008
> >
> > Philipp Meinen wrote:
> > > Hello FFmpeg Team
> > >
> > > The attached patch is an attempt to allow runtime detection for
> > > the
> > > number of online processors/cores instead of having to specify
> > > the
> > > number of threads. The idea is to type:
> > > ffmpeg -threads 0 ....
> > > to use as many threads as processors/cores are online.
> > >
> > > I guess cmdutils.c/h is not the right file to place the new
> > > detection function. To which file should this function belong?
> > >
> > > Comments welcome :)
> >
> > This is the wrong way to go about it. The number of processors in
> > the
> > machine is not interesting, the number of processors we're running
> > on
> > is. On Linux, this information can be found from
> > sched_get_affinity().
> > Other systems have other methods.
>
> _SC_NPROCESSORS_ONLN Number of processors online
>
> Seems to mean the same to me, unlike:
Unless of course sched_get_affinity() returns a subset mask for NUMA
machines, then disregard.
It's POSIX only anyway so it has to be platform dependant...
Hmm doesn't pthread have a less linuxish call for that btw ?
Else one can still #ifdef __linux__ to use sched_get_affinity and fall
back to sysconf.
Fran?ois.
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