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SubjectRe: [PATCH v3 5/9] x86/mm/tlb: Privatize cpu_tlbstate
Date
> On Jul 19, 2019, at 11:38 AM, Dave Hansen <dave.hansen@intel.com> wrote:
>
> On 7/18/19 5:58 PM, Nadav Amit wrote:
>> +struct tlb_state_shared {
>> + /*
>> + * We can be in one of several states:
>> + *
>> + * - Actively using an mm. Our CPU's bit will be set in
>> + * mm_cpumask(loaded_mm) and is_lazy == false;
>> + *
>> + * - Not using a real mm. loaded_mm == &init_mm. Our CPU's bit
>> + * will not be set in mm_cpumask(&init_mm) and is_lazy == false.
>> + *
>> + * - Lazily using a real mm. loaded_mm != &init_mm, our bit
>> + * is set in mm_cpumask(loaded_mm), but is_lazy == true.
>> + * We're heuristically guessing that the CR3 load we
>> + * skipped more than makes up for the overhead added by
>> + * lazy mode.
>> + */
>> + bool is_lazy;
>> +};
>> +DECLARE_PER_CPU_SHARED_ALIGNED(struct tlb_state_shared, cpu_tlbstate_shared);
>
> Could we get a comment about what "shared" means and why we need shared
> state?
>
> Should we change 'tlb_state' to 'tlb_state_private’?

I don’t feel strongly about either one. I perferred the one that is likely
to cause fewer changes and potential conflicts. Anyhow, I would add a better
comment as you asked for.

So it is really up to you.

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