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Date:   Wed, 4 Oct 2023 15:52:36 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Florian Weimer <fweimer@redhat.com>
Cc:     Waiman Long <longman@redhat.com>, Ingo Molnar <mingo@redhat.com>,
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        linux-kernel@vger.kernel.org, Phil Auld <pauld@redhat.com>,
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Subject: Re: [PATCH v4] sched/core: Use zero length to reset cpumasks in
 sched_setaffinity()
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On Wed, Oct 04, 2023 at 02:34:15PM +0200, Florian Weimer wrote:
> * Peter Zijlstra:
> 
> > Subject: sched: Add CPU_FILL()
> >
> > Add the CPU_FILL() macros to easily create an all-set cpumask.
> >
> > FreeBSD also provides this macro with this semantic.
> >
> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> 
> My main concer is that obtaining the size of the mask, or at least an
> approximiation is not exactly easy.  If there's an expectation that
> applications reset the mask more often than they do today (I don't have
> the full context here), then we'd some decent interface to get the
> approriate size.

Isn't sysconf(_SC_NPROCESSORS_CONF) the right number ?