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Date: Mon, 29 Nov 2021 08:26:55 +0000
From: Mel Gorman <mgorman@techsingularity.net>
To: Mike Galbraith <efault@gmx.de>
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>
Subject: Re: [PATCH 1/1] mm: vmscan: Reduce throttling due to a failure to
 make progress
Message-ID: <20211129082654.GM3366@techsingularity.net>
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On Sun, Nov 28, 2021 at 11:00:59AM +0100, Mike Galbraith wrote:
> On Sun, 2021-11-28 at 04:26 +0900, Alexey Avramov wrote:
> > I will present the results of the new tests here.
> >
> > TLDR;
> > =====
> > No one Mel's patch doesn't prevent stalls in my tests.
> 
> Seems there may be a problem with the THROTTLE_WRITEBACK bits..
> 
> > $ for i in {1..10}; do tail /dev/zero; done
> > -- 1. with noswap
> 
> ..because the bandaid below (made of 8cd7c588 shards) on top of Mel's
> last pulled that one-liner's very pointy fangs.
> 

This disables writeback throttling in most cases as bdi congested is not
updated by the block layer.

-- 
Mel Gorman
SUSE Labs