linux-kernel - Re: [RFC PATCH 00/16] mm/madvise: batch tlb flushes for MADV_DONTNEED and MADV

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Message-Id: <7BC81F7C-191F-451D-8FE5-5BB268F6B0A1@gmail.com>
Date: Wed, 5 Mar 2025 22:36:45 +0200
From: Nadav Amit <nadav.amit@...il.com>
To: SeongJae Park <sj@...nel.org>
Cc: "Liam R. Howlett" <howlett@...il.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 David Hildenbrand <david@...hat.com>,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 Shakeel Butt <shakeel.butt@...ux.dev>,
 Vlastimil Babka <vbabka@...e.cz>,
 kernel-team@...a.com,
 Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
 "open list:MEMORY MANAGEMENT" <linux-mm@...ck.org>
Subject: Re: [RFC PATCH 00/16] mm/madvise: batch tlb flushes for MADV_DONTNEED
 and MADV_FREE

> On 5 Mar 2025, at 20:15, SeongJae Park <sj@...nel.org> wrote:
> 
> For MADV_DONTNEED[_LOCKED] or MADV_FREE madvise requests, tlb flushes
> can happen for each vma of the given address ranges.  Because such tlb
> flushes are for address ranges of same process, doing those in a batch
> is more efficient while still being safe.  Modify madvise() and
> process_madvise() entry level code path to do such batched tlb flushes,
> while the internal unmap logics do only gathering of the tlb entries to
> flush.

I made some related (similar?) patches in the past. You can see if you
find something useful in the discussion there. I think your version avoids
some of the “mistakes” I made.

[1] https://lore.kernel.org/all/20210926161259.238054-1-namit@vmware.com/T/#m23ccd29bad04a963c4d8c64ec3581f7c301c7806