Re: [PATCH v10 00/12] LUF(Lazy Unmap Flush) reducing tlb numbers over 90%

Huang, Ying
2024-05-11T07:16:58Z

Byungchul Park <byungchul@sk.com> writes:

> Hi everyone,
>
> While I'm working with a tiered memory system e.g. CXL memory, I have
> been facing migration overhead esp. tlb shootdown on promotion or
> demotion between different tiers. Yeah.. most tlb shootdowns on
> migration through hinting fault can be avoided thanks to Huang Ying's
> work, commit 4d4b6d66db ("mm,unmap: avoid flushing tlb in batch if PTE
> is inaccessible"). See the following link for more information:
>
> https://lore.kernel.org/lkml/20231115025755.GA29979@system.software.com/

And, I still have interest of the performance impact of commit
7e12beb8ca2a ("migrate_pages: batch flushing TLB"). In the email above,
you said that the performance of v6.5-rc5 + 7e12beb8ca2a reverted has
better performance than v6.5-rc5. Can you provide more details? For
example, the number of TLB flushing IPI for two kernels?

I should have followed up the above email. Sorry about that. Anyway,
we should try to fix issue of that commit too.

--
Best Regards,
Huang, Ying

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