Re: [PATCH v1 0/2] Ignore non-LRU-based reclaim in memcg reclaim

From: Yosry Ahmed <yosryahmed@google.com>
To: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	"Darrick J. Wong" <djwong@kernel.org>,
	Christoph Lameter <cl@linux.com>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Roman Gushchin <roman.gushchin@linux.dev>,
	Hyeonggon Yoo <42.hyeyoo@gmail.com>,
	"Matthew Wilcox (Oracle)" <willy@infradead.org>,
	Miaohe Lin <linmiaohe@huawei.com>,
	David Hildenbrand <david@redhat.com>,
	Peter Xu <peterx@redhat.com>, NeilBrown <neilb@suse.de>,
	Shakeel Butt <shakeelb@google.com>,
	Michal Hocko <mhocko@kernel.org>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-xfs@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v1 0/2] Ignore non-LRU-based reclaim in memcg reclaim
Date: Wed, 8 Mar 2023 13:31:34 -0800	[thread overview]
Message-ID: <CAJD7tkbu97JWOEvRJDYBKzy5qOJ8LYK6ZXBJSDhUw0+8br_Dqg@mail.gmail.com> (raw)
In-Reply-To: <20230308212529.GL360264@dread.disaster.area>

On Wed, Mar 8, 2023 at 1:25 PM Dave Chinner <david@fromorbit.com> wrote:
>
> On Wed, Mar 08, 2023 at 12:24:08PM -0800, Yosry Ahmed wrote:
> > > I tried to come up with something better, but wasn't happy with any of
> > > the options, either. So I defaulted to just leaving it alone :-)
> > >
> > > It's part of the shrinker API and the name hasn't changed since the
> > > initial git import of the kernel tree. It should be fine, churn-wise.
> >
> > Last attempt, just update_reclaim_state() (corresponding to
> > flush_reclaim_state() below). It doesn't tell a story, but neither
> > does incrementing a counter in current->reclaim_state. If that doesn't
> > make you happy I'll give up now and leave it as-is :)
>
> This is used in different subsystem shrinkers outside mm/, so the
> name needs to be correctly namespaced. Please prefix it with the
> subsystem the function belongs to, at minimum.
>
> mm_account_reclaimed_pages() is what is actually being done here.
> It is self describing  and leaves behind no ambiguity as to what is
> being accounted and why, nor which subsystem the accounting belongs
> to.
>
> It doesn't matter what the internal mm/vmscan structures are called,
> all we care about is telling the mm infrastructure how many extra
> pages were freed by the shrinker....

mm_account_reclaimed_pages() sounds good to me. We can also do
something more specific if Johannes has any ideas. I do not have a
strong opinion here at all, I just prefer having a helper to leaving
it open-coded.

Thanks!

>
> -Dave.
> --
> Dave Chinner
> david@fromorbit.com