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SubjectRe: [PATCH 16/28] x86/intel_rdt: Prepare to add RDT monitor cpus file support


On Tue, 1 Aug 2017, Thomas Gleixner wrote:

> On Tue, 25 Jul 2017, Vikas Shivappa wrote:
>> /*
>> * The cached intel_pqr_state is strictly per CPU and can never be
>> * updated from a remote CPU. Functions which modify the state
>> @@ -49,6 +47,8 @@
>> */
>> DEFINE_PER_CPU(struct intel_pqr_state, pqr_state);
>>
>> +DEFINE_PER_CPU_READ_MOSTLY(struct intel_pqr_state, rdt_cpu_default);
>
> Cacheline wise this is suboptimal. You have to touch two cachelines on each
> context switch (at least for read).
>
> If you make that:
>
> struct intel_pqr_state {
> u32 default_cosid;
> u32 default_rmid;
> u32 cur_cosid;
> u32 cur_rmid;
> };
>
> DEFINE_PER_CPU(struct intel_pqr_state, pqr_state);
>
> then it's all together and you spare one cache line.

Will fix..

Thanks,
Vikas

>
> Thanks,
>
> tglx
>

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