linux-kernel - Re: [PATCH v2 0/3] Optimizations for khugepaged

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Message-ID: <d684d89d-59ac-435a-b5c9-22f3dc3eea03@lucifer.local>
Date: Wed, 25 Jun 2025 11:36:36 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Dev Jain <dev.jain@....com>
Cc: akpm@...ux-foundation.org, david@...hat.com, ziy@...dia.com,
        baolin.wang@...ux.alibaba.com, Liam.Howlett@...cle.com,
        npache@...hat.com, ryan.roberts@....com, baohua@...nel.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/3] Optimizations for khugepaged

On Wed, Jun 25, 2025 at 11:28:03AM +0530, Dev Jain wrote:
> This patch series uses PTE batching to optimize two functions, and
> also addresses a race condition.

Kinda succinct, be nice to expand a little. I know it can end up being a
little duplicative, but I think more information is always better than less
(as long as not truly overwrought)

>
> ---
> @David I did not make the clear_full_ptes clean up since that will require
> some more work than I originally thought :)
>
> v1->v2:
>  - Use for loop instead of do-while loop (Lorenzo)
>  - Remove folio_test_large check since the subpage-check condition
>    will imply that (Baolin)
>  - Combine patch 1 and 2 into this series, add new patch 3

One small nit, it'd be really handy to include links to previous series to
help us find them :P

As this one combines a couple earlier (which is nice!) but handy just for
comparison's sake :>)

>
> Dev Jain (3):
>   khugepaged: Optimize __collapse_huge_page_copy_succeeded() by PTE
>     batching
>   khugepaged: Optimize collapse_pte_mapped_thp() for large folios by PTE
>     batching
>   khugepaged: Reduce race probability between migration and khugepaged
>
>  mm/khugepaged.c | 77 ++++++++++++++++++++++++++++++++++++-------------
>  1 file changed, 57 insertions(+), 20 deletions(-)
>
> --
> 2.30.2
>