linux-kernel - Re: [PATCH 2/2 v2] perf bench futex: add NUMA support

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Date:   Thu, 20 Oct 2016 19:34:14 -0700
From:   Davidlohr Bueso <dave@...olabs.net>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...hat.com>, Jiri Olsa <jolsa@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        Davidlohr Bueso <dbueso@...e.de>
Subject: Re: [PATCH 2/2 v2] perf bench futex: add NUMA support

On Wed, 19 Oct 2016, Sebastian Andrzej Siewior wrote:

>On 2016-10-19 11:16:16 [-0700], Davidlohr Bueso wrote:
>> On Mon, 17 Oct 2016, Sebastian Andrzej Siewior wrote:
>>
>> > By default the application uses malloc() and all available CPUs. This
>> > patch introduces NUMA support which means:
>> > - memory is allocated node local via numa_alloc_local()
>> > - all CPUs of the specified NUMA node are used. This is also true if the
>> >  number of threads set is greater than the number of CPUs available on
>> >  this node.
>>
>> Can't we just use numactl to bind cpus and memory to be node-local?
>
>something like
>	numactl --cpunodebind=$NODE --membind=$NODE perf ???
>?

Yes.

>This should work for memory however since we use
>	pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpu);
>we would need to query the affinity mask, and deploy threads based on
>that mask.

Ah right. I also considered getting rid of the affinity, but that would
probably hurt more than help (or at least alter) for non-numa options.

>Using NUMA support within this bench-tool has also the side effect that
>the output gives all the option used.

So if we are going to support the numa option for the benchmark, could you please
move the new code into futex.h instead of futex-hash.c? That way we can integrate
the support for the other futex programs as well.

Thanks,
Davidlohr