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From: David Sterba <dsterba@suse.cz>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: Matthew Wilcox <willy@infradead.org>,
	Linux-MM <linux-mm@kvack.org>, NeilBrown <neilb@suse.de>,
	Theodore Ts'o <tytso@mit.edu>,
	Andreas Dilger <adilger.kernel@dilger.ca>,
	"Darrick J . Wong" <djwong@kernel.org>,
	Michal Hocko <mhocko@suse.com>,
	Dave Chinner <david@fromorbit.com>,
	Rik van Riel <riel@surriel.com>, Vlastimil Babka <vbabka@suse.cz>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 0/5] Remove dependency on congestion_wait in mm/
Date: Mon, 20 Sep 2021 16:11:52 +0200	[thread overview]
Message-ID: <20210920141152.GM9286@twin.jikos.cz> (raw)
In-Reply-To: <20210920125058.GI3959@techsingularity.net>

On Mon, Sep 20, 2021 at 01:50:58PM +0100, Mel Gorman wrote:
> On Mon, Sep 20, 2021 at 12:42:44PM +0100, Matthew Wilcox wrote:
> > On Mon, Sep 20, 2021 at 09:54:31AM +0100, Mel Gorman wrote:
> > > This has been lightly tested only and the testing was useless as the
> > > relevant code was not executed. The workload configurations I had that
> > > used to trigger these corner cases no longer work (yey?) and I'll need
> > > to implement a new synthetic workload. If someone is aware of a realistic
> > > workload that forces reclaim activity to the point where reclaim stalls
> > > then kindly share the details.
> > 
> > The stereeotypical "stalling on I/O" problem is to plug in one of the
> > crap USB drives you were given at a trade show and simply
> > 	dd if=/dev/zero of=/dev/sdb
> > 	sync
> > 
> 
> The test machines are 1500KM away so plugging in a USB stick but worst
> comes to the worst, I could test it on a laptop.

There's a device mapper target dm-delay [1] that as it says delays the
reads and writes, so you could try to emulate the slow USB that way.

[1] https://www.kernel.org/doc/html/latest/admin-guide/device-mapper/delay.html

  reply	other threads:[~2021-09-20 14:12 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-20  8:54 Mel Gorman
2021-09-20  8:54 ` [PATCH 1/5] mm/vmscan: Throttle reclaim until some writeback completes if congested Mel Gorman
2021-09-20 23:19   ` NeilBrown
2021-09-21 11:12     ` Mel Gorman
2021-09-21 21:27       ` NeilBrown
2021-09-21  0:13   ` NeilBrown
2021-09-21 10:58     ` Mel Gorman
2021-09-21 21:40       ` NeilBrown
2021-09-22  6:04       ` Dave Chinner
2021-09-22  8:03         ` Mel Gorman
2021-09-22 12:16   ` Hillf Danton
2021-09-22 14:13     ` Mel Gorman
2021-09-20  8:54 ` [PATCH 2/5] mm/vmscan: Throttle reclaim and compaction when too may pages are isolated Mel Gorman
2021-09-20 23:27   ` NeilBrown
2021-09-21 11:03     ` Mel Gorman
2021-09-21 18:45   ` Yang Shi
2021-09-21 18:45     ` Yang Shi
2021-09-22  8:11     ` Mel Gorman
2021-09-20  8:54 ` [PATCH 3/5] mm/vmscan: Throttle reclaim when no progress is being made Mel Gorman
2021-09-20 23:31   ` NeilBrown
2021-09-21 11:16     ` Mel Gorman
2021-09-21 21:46       ` NeilBrown
2021-09-22  9:21         ` Mel Gorman
2021-09-20  8:54 ` [PATCH 4/5] mm/writeback: Throttle based on page writeback instead of congestion Mel Gorman
2021-09-20  8:54 ` [PATCH 5/5] mm/page_alloc: Remove the throttling logic from the page allocator Mel Gorman
2021-09-20 11:42 ` [RFC PATCH 0/5] Remove dependency on congestion_wait in mm/ Matthew Wilcox
2021-09-20 12:50   ` Mel Gorman
2021-09-20 14:11     ` David Sterba [this message]
2021-09-21 11:18       ` Mel Gorman
2021-09-20 19:51   ` Mel Gorman
2021-09-21 20:46 ` Dave Chinner
2021-09-22 17:52   ` Mel Gorman

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