[PATCH v5 1/2] powerpc/vcpu: Assume dedicated processors as non-preempt

[Michael Ellerman]

Srikar Dronamraju <srikar at linux.vnet.ibm.com> writes:
> * Michael Ellerman <mpe at ellerman.id.au> [2019-12-13 14:50:35]:
>
>> Waiman Long suggested using static_keys.
>> 
>> Fixes: 247f2f6f3c70 ("sched/core: Don't schedule threads on pre-empted vCPUs")
>> Cc: stable at vger.kernel.org # v4.18+
>> Reported-by: Parth Shah <parth at linux.ibm.com>
>> Reported-by: Ihor Pasichnyk <Ihor.Pasichnyk at ibm.com>
>> Tested-by: Juri Lelli <juri.lelli at redhat.com>
>> Acked-by: Waiman Long <longman at redhat.com>
>> Reviewed-by: Gautham R. Shenoy <ego at linux.vnet.ibm.com>
>> Signed-off-by: Srikar Dronamraju <srikar at linux.vnet.ibm.com>
>> Acked-by: Phil Auld <pauld at redhat.com>
>> Reviewed-by: Vaidyanathan Srinivasan <svaidy at linux.ibm.com>
>> Tested-by: Parth Shah <parth at linux.ibm.com>
>> [mpe: Move the key and setting of the key to pseries/setup.c]
>> Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
>> ---
>>  arch/powerpc/include/asm/spinlock.h    | 4 +++-
>>  arch/powerpc/platforms/pseries/setup.c | 7 +++++++
>>  2 files changed, 10 insertions(+), 1 deletion(-)
>> 
>
> Tested with your version of the patch and its working as expected

Thanks, I took the values below and put them in the changelog for the
patched case.

cheers

> Latency percentiles (usec)
>         50.0th: 45
>         75.0th: 63
>         90.0th: 74
>         95.0th: 78
>         *99.0th: 82
>         99.5th: 83
>         99.9th: 86
>         min=0, max=96
> Latency percentiles (usec)
>         50.0th: 46
>         75.0th: 64
>         90.0th: 75
>         95.0th: 79
>         *99.0th: 83
>         99.5th: 85
>         99.9th: 91
>         min=0, max=117
> Latency percentiles (usec)
>         50.0th: 46
>         75.0th: 64
>         90.0th: 75
>         95.0th: 79
>         *99.0th: 83
>         99.5th: 84
>         99.9th: 90
>         min=0, max=95
> Latency percentiles (usec)
>         50.0th: 47
>         75.0th: 65
>         90.0th: 75
>         95.0th: 79
>         *99.0th: 84
>         99.5th: 85
>         99.9th: 90
>         min=0, max=117
> Latency percentiles (usec)
>         50.0th: 45
>         75.0th: 64
>         90.0th: 75
>         95.0th: 79
>         *99.0th: 82
>         99.5th: 83
>         99.9th: 93
>         min=0, max=111
>
>
> -- 
> Thanks and Regards
> Srikar Dronamraju