Messages in this thread | | | Date | Thu, 10 Oct 2013 00:33:15 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 0/6] Optimize the cpu hotplug locking -v2 |
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On Thu, 10 Oct 2013 09:27:57 +0200 Ingo Molnar <mingo@kernel.org> wrote:
> > > Should be fairly straightforward to test: the sys_sched_getaffinity() > > > and sys_sched_setaffinity() syscalls both make use of > > > get_online_cpus()/put_online_cpus(), so a testcase frobbing affinities > > > on N CPUs in parallel ought to demonstrate scalability improvements > > > pretty nicely. > > > > Well, an in-kernel microbenchmark which camps in a loop doing get/put > > would measure this as well. > > > > But neither approach answers the question "how useful is this patchset". > > Even ignoring all the other reasons cited, sys_sched_getaffinity() / > sys_sched_setaffinity() are prime time system calls, and as long as the > patches are correct, speeding them up is worthwhile.
That I would not have guessed. What's the use case for calling get/set_affinity at high frequency?
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