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SubjectRe: [PATCH] x86: Run checksumming in parallel accross multiple alu's
On Mon, Oct 28, 2013 at 05:24:38PM +0100, Ingo Molnar wrote:
>
> * Neil Horman <nhorman@tuxdriver.com> wrote:
>
> > Looking at the specific cpu counters we get this:
> >
> > Base:
> > Total time: 0.179 [sec]
> >
> > Performance counter stats for 'perf bench sched messaging -- bash -c echo 1 > /sys/module/csum_test/parameters/test_fire' (20 runs):
> >
> > 1571.304618 task-clock # 5.213 CPUs utilized ( +- 0.45% )
> > 14,423 context-switches # 0.009 M/sec ( +- 4.28% )
> > 2,710 cpu-migrations # 0.002 M/sec ( +- 2.83% )
>
> Hm, for these second round of measurements were you using 'perf stat
> -a -C ...'?
>
> The most accurate method of measurement for such single-threaded
> workloads is something like:
>
> taskset 0x1 perf stat -a -C 1 --repeat 20 ...
>
> this will bind your workload to CPU#0, and will do PMU measurements
> only there - without mixing in other CPUs or workloads.
>
> Thanks,
>
> Ingo
I wasn't, but I will...
Neil

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