Re: [PATCH 5/9] x86/mm/tlb: Optimize local TLB flushes

From: Nadav Amit
Date: Wed Jun 26 2019 - 12:39:05 EST

> On Jun 26, 2019, at 9:33 AM, Andy Lutomirski <luto@xxxxxxxxxx> wrote:
> On Tue, Jun 25, 2019 at 2:36 PM Dave Hansen <dave.hansen@xxxxxxxxx> wrote:
>> On 6/12/19 11:48 PM, Nadav Amit wrote:
>>> While the updated smp infrastructure is capable of running a function on
>>> a single local core, it is not optimized for this case.
>> OK, so flush_tlb_multi() is optimized for flushing local+remote at the
>> same time and is also (near?) the most optimal way to flush remote-only.
>> But, it's not as optimized at doing local-only flushes. But,
>> flush_tlb_on_cpus() *is* optimized for local-only flushes.
> Can we stick the optimization into flush_tlb_multi() in the interest
> of keeping this stuff readable?

flush_tlb_on_cpus() will be much simpler once I remove the fallback
path that is in there for Xen and hyper-v. I can then open-code it in
flush_tlb_mm_range() and arch_tlbbatch_flush().

> Also, would this series be easier to understand if there was a patch
> to just remove the UV optimization before making other changes?

If you just want me to remove it, I can do it. I donât know who uses it and
what the impact might be.