linux-kernel - Re: [PATCH v3] mm: add thp_utilization metrics to /proc/thp

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Date:   Mon, 8 Aug 2022 18:35:06 +0000
From:   Rik van Riel <riel@...com>
To:     "Alex Zhu (Kernel)" <alexlzhu@...com>,
        "shy828301@...il.com" <shy828301@...il.com>
CC:     Kernel Team <Kernel-team@...com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "willy@...radead.org" <willy@...radead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
Subject: Re: [PATCH v3] mm: add thp_utilization metrics to
 /proc/thp_utilization

On Mon, 2022-08-08 at 10:55 -0700, Yang Shi wrote:
> 
> On Fri, Aug 5, 2022 at 12:52 PM Alex Zhu (Kernel) <alexlzhu@...com>
> wrote:
> > 
> > Sounds good, I’ll move this to debugfs then. Will follow up with
> > the shrinker code
> > in another patch. The shrinker relies on this scanning thread to
> > figure out which
> > THPs to reclaim.
> 
> I'm wondering whether you could reuse the THP deferred split shrinker
> or not. It is already memcg aware.
> 
I'm not convinced that will buy much, since there is
very little code duplication between the two.

Merging the two might also bring about another bit of
extra complexity, due to the deferred split shrinker
wanting to shrink every single THP on its "to split"
list, while for Alex's shrinker we probably want to
split just one (or a few) THPs at a time, depending on
memory pressure.