linux-kernel - Re: [PATCH v2] mm: add access/dirty bit on numa page fault

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Date:   Fri, 18 Mar 2022 10:17:35 +0800
From:   maobibo <maobibo@...ngson.cn>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Anshuman Khandual <anshuman.khandual@....com>
Subject: Re: [PATCH v2] mm: add access/dirty bit on numa page fault



On 03/18/2022 09:46 AM, Matthew Wilcox wrote:
> On Fri, Mar 18, 2022 at 09:01:32AM +0800, maobibo wrote:
>>> Is this a correctness problem, in which case this will need to be
>>> backported, or is this a performance problem, in which case can you
>>> share some numbers?
>> It is only performance issue, and there is no obvious performance
>> improvement for general workloads on my hand, but I do not test
>> it on microbenchmark.
> 
> ... if there's no performance improvement, why should we apply this
> patch?  Confused.
> 
It is not obvious from workload view, it actually reduces one tlb miss
on platforms without hw page walk.