linux-kernel - Re: [PATCH v4 0/3] Optimize large folio interaction with deferred split

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Message-ID: <20230803120100.2glxdc4yf7sjn7h5@box.shutemov.name>
Date:   Thu, 3 Aug 2023 15:01:00 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     Ryan Roberts <ryan.roberts@....com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Matthew Wilcox <willy@...radead.org>,
        Yin Fengwei <fengwei.yin@...el.com>,
        David Hildenbrand <david@...hat.com>,
        Yu Zhao <yuzhao@...gle.com>, Yang Shi <shy828301@...il.com>,
        "Huang, Ying" <ying.huang@...el.com>, Zi Yan <ziy@...dia.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Gerald Schaefer <gerald.schaefer@...ux.ibm.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v4 0/3] Optimize large folio interaction with deferred
 split

On Wed, Aug 02, 2023 at 05:42:23PM +0100, Ryan Roberts wrote:
>  - avoid the split lock contention by using mmu gather (suggested by Kirill)

[Offlist]

So, my idea is to embed struct deferred_split into struct mmu_gather and
make zap path to use it instead of per-node/per-memcg deferred_split. This
would avoid lock contention. If the list is not empty after zap, move the
to the per-node/per-memcg deferred_split.

But it is only relevant if we see lock contention.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov