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Subject: Re: [hwloc-users] bind process to built cpuset
From: Brice Goglin (Brice.Goglin_at_[hidden])
Date: 2012-02-20 13:09:55


Le 20/02/2012 19:06, Brice Goglin a écrit :
> Le 20/02/2012 17:41, Albert Solernou a écrit :
>> Hi,
>> I'd like to bind a process to a cpuset, so that when it spawns on
>> several threads, those are trapped on that cpuset.
>>
>> In order to do so, I want to define my own cpuset. Let's say I want it
>> to include HWLOC_OBJ_CORE 2 and 5. How can I create this cpuset? The
>> bitmap api sounds like the solution to me, but I couldn't relate the
>> indexes in there into HWLOC_OBJects of any type...
> If you want to bind to cores #2 and #5, do:
>
> hwloc_bitmap_t cpuset;
> hwloc_obj_t core1, core2;
>
> core1 = hwloc_get_obj_by_type(topology, HWLOC_OBJ_CORE, 2);
> if (!core1)
> error...
> core2 = hwloc_get_obj_by_type(topology, HWLOC_OBJ_CORE, 5);
> if (!core2)
> error...
> cpuset = hwloc_bitmap_alloc();
> if (!cpuset);
> error...
> hwloc_bitmap_or(cpuset, cpuset, core1->cpuset);
> hwloc_bitmap_or(cpuset, cpuset, core2->cpuset);

By the way, alloc()+or() can be optimized as dup():

cpuset = hwloc_bitmap_dup(core1->cpuset);
if (!cpuset)
   error...
hwloc_bitmap_or(cpuset, cpuset, core2->cpuset);

Brice