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

[Srikar Dronamraju]

* 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

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