Message-ID: <b966ccc578ac60d3684cff0c88c1b9046b408ea3.camel@gmx.de>
Subject: Re: [PATCH 1/1] mm: vmscan: Reduce throttling due to a failure to
 make progress
From:   Mike Galbraith <efault@gmx.de>
To:     Mel Gorman <mgorman@techsingularity.net>
Cc:     Alexey Avramov <hakavlad@inbox.lv>,
        Andrew Morton <akpm@linux-foundation.org>,
        Michal Hocko <mhocko@suse.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Rik van Riel <riel@surriel.com>,
        Darrick Wong <djwong@kernel.org>, regressions@lists.linux.dev,
        Linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Linux-MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>
Date:   Tue, 30 Nov 2021 13:51:10 +0100
In-Reply-To: <b8f607c771a4f698fcb651379ca30d3bb6a83ccd.camel@gmx.de>
References: <20211125151853.8540-1-mgorman@techsingularity.net>
         <20211127011246.7a8ac7b8@mail.inbox.lv>
         <20211129150117.GO3366@techsingularity.net>
         <a20f17c4b1b5fdfade3f48375d148e97bd162dd6.camel@gmx.de>
         <20211130112244.GQ3366@techsingularity.net>
         <b8f607c771a4f698fcb651379ca30d3bb6a83ccd.camel@gmx.de>
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On Tue, 2021-11-30 at 13:00 +0100, Mike Galbraith wrote:
> On Tue, 2021-11-30 at 11:22 +0000, Mel Gorman wrote:
> > On Tue, Nov 30, 2021 at 11:14:32AM +0100, Mike Galbraith wrote:
> > > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0}
> > > > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0if (2 * write_pending <=
=3D reclaimable)
> > >
> > > That is always true here...
> > >
> >
> > Always true for you or always true in general?
>
> "Here" as in the boxen located at my GPS coordinates :)
>
> > The intent of the check is "are a majority of reclaimable pages
> > marked WRITE_PENDING?". It's similar to the check that existed prior
> > to 132b0d21d21f ("mm/page_alloc: remove the throttling logic from the
> > page allocator").
>
> I'll put my trace_printk() back and see if I can't bend-adjust it.

As it sits, write_pending is always 0 with tail /dev/zero.

	-Mike