linux-kernel - Re: [PATCH] mm/vmstat: Reduce zone lock hold time when reading /proc/pagetypeinfo

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Message-Id: <B292E9D2-D619-4A57-BBE3-A4D10826AA60@lca.pw>
Date:   Thu, 24 Oct 2019 07:11:52 -0400
From:   Qian Cai <cai@....pw>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Waiman Long <longman@...hat.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Johannes Weiner <hannes@...xchg.org>,
        Roman Gushchin <guro@...com>, Vlastimil Babka <vbabka@...e.cz>,
        Konstantin Khlebnikov <khlebnikov@...dex-team.ru>,
        Jann Horn <jannh@...gle.com>, Song Liu <songliubraving@...com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rafael Aquini <aquini@...hat.com>
Subject: Re: [PATCH] mm/vmstat: Reduce zone lock hold time when reading /proc/pagetypeinfo



> On Oct 24, 2019, at 3:42 AM, Michal Hocko <mhocko@...nel.org> wrote:
> 
> It's been useful for debugging memory fragmentation problems and we do
> not have anything that would provide a similar information. Considering

Actually, zoneinfo and buddyinfo are somewhat similar to it. Why the extra information in pagetypeinfo is still useful in debugging today’s real-world scenarios?

> that making it root only is trivial and reducing the lock hold times
> likewise I do not really see any strong reason to dump it at this
> moment.

There is no need to hurry this, and clearly this is rather a good opportunity to discuss the consolidation of memory fragmentation debugging to ease the maintenance in long term.