From: Mel Gorman <firstname.lastname@example.org> To: email@example.com, Matthew Wilcox <firstname.lastname@example.org>, Linux-MM <email@example.com>, NeilBrown <firstname.lastname@example.org>, Theodore Ts'o <email@example.com>, Andreas Dilger <firstname.lastname@example.org>, "Darrick J . Wong" <email@example.com>, Michal Hocko <firstname.lastname@example.org>, Dave Chinner <email@example.com>, Rik van Riel <firstname.lastname@example.org>, Vlastimil Babka <email@example.com>, Johannes Weiner <firstname.lastname@example.org>, Jonathan Corbet <email@example.com>, Linux-fsdevel <firstname.lastname@example.org>, LKML <email@example.com> Subject: Re: [RFC PATCH 0/5] Remove dependency on congestion_wait in mm/ Date: Tue, 21 Sep 2021 12:18:17 +0100 [thread overview] Message-ID: <20210921111816.GS3959@techsingularity.net> (raw) In-Reply-To: <20210920141152.GM9286@twin.jikos.cz> On Mon, Sep 20, 2021 at 04:11:52PM +0200, David Sterba wrote: > 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  that as it says delays the > reads and writes, so you could try to emulate the slow USB that way. > >  https://www.kernel.org/doc/html/latest/admin-guide/device-mapper/delay.html Ah, thanks for that tip. I wondered if something like this existed and clearly did not search hard enough. I was able to reproduce the problem without throttling but this could still be useful if examining cases where there are 2 or more BDIs with variable speeds. -- Mel Gorman SUSE Labs
next prev parent reply other threads:[~2021-09-21 11:18 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 2021-09-21 11:18 ` Mel Gorman [this message] 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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