From: Mel Gorman <mgorman@suse.de>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kernel-team@fb.com
Subject: Re: [PATCH 2/5] mm: vmscan: kick flushers when we encounter dirty pages on the LRU
Date: Thu, 26 Jan 2017 18:47:45 +0000 [thread overview]
Message-ID: <20170126184745.pa3nxlsbjzvbgvdk@suse.de> (raw)
In-Reply-To: <20170126174739.GA30636@cmpxchg.org>
On Thu, Jan 26, 2017 at 12:47:39PM -0500, Johannes Weiner wrote:
> On Thu, Jan 26, 2017 at 09:57:45AM +0000, Mel Gorman wrote:
> > On Mon, Jan 23, 2017 at 01:16:38PM -0500, Johannes Weiner wrote:
> > > Memory pressure can put dirty pages at the end of the LRU without
> > > anybody running into dirty limits. Don't start writing individual
> > > pages from kswapd while the flushers might be asleep.
> > >
> > > Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
> >
> > I don't understand the motivation for checking the wb_reason name. Maybe
> > it was easier to eyeball while reading ftraces. The comment about the
> > flusher not doing its job could also be as simple as the writes took
> > place and clean pages were reclaimed before dirty_expire was reached.
> > Not impossible if there was a light writer combined with a heavy reader
> > or a large number of anonymous faults.
>
> The name change was only because try_to_free_pages() wasn't the only
> function doing this flusher wakeup anymore.
Ah, ok. I was thinking of it in terms of "we are trying to free pages"
and not the specific name of the direct reclaim function.
> I associate that name with
> direct reclaim rather than reclaim in general, so I figured this makes
> more sense. No strong feelings either way, but I doubt this will break
> anything in userspace.
>
Doubtful, maybe some tracing analysis scripts but they routinely have
to adapt.
> The comment on dirty expiration is a good point. Let's add this to the
> list of reasons why reclaim might run into dirty data. Fixlet below.
>
Looks good.
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2017-01-26 18:47 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-23 18:16 [PATCH 0/5] mm: vmscan: fix kswapd writeback regression Johannes Weiner
2017-01-23 18:16 ` [PATCH 1/5] mm: vmscan: scan dirty pages even in laptop mode Johannes Weiner
2017-01-26 1:27 ` Minchan Kim
2017-01-26 9:52 ` Mel Gorman
2017-01-26 13:13 ` Michal Hocko
2017-01-23 18:16 ` [PATCH 2/5] mm: vmscan: kick flushers when we encounter dirty pages on the LRU Johannes Weiner
2017-01-26 1:35 ` Minchan Kim
2017-01-26 9:57 ` Mel Gorman
2017-01-26 17:47 ` Johannes Weiner
2017-01-26 18:47 ` Mel Gorman [this message]
2017-01-26 13:16 ` Michal Hocko
2017-01-23 18:16 ` [PATCH 3/5] mm: vmscan: remove old flusher wakeup from direct reclaim path Johannes Weiner
2017-01-26 1:38 ` Minchan Kim
2017-01-26 10:05 ` Mel Gorman
2017-01-26 18:50 ` Johannes Weiner
2017-01-26 20:45 ` Mel Gorman
2017-01-27 12:01 ` Michal Hocko
2017-01-27 14:27 ` Mel Gorman
2017-01-26 13:21 ` Michal Hocko
2017-01-23 18:16 ` [PATCH 4/5] mm: vmscan: only write dirty pages that the scanner has seen twice Johannes Weiner
2017-01-26 1:42 ` Minchan Kim
2017-01-26 10:08 ` Mel Gorman
2017-01-26 13:29 ` Michal Hocko
2017-01-23 18:16 ` [PATCH 5/5] mm: vmscan: move dirty pages out of the way until they're flushed Johannes Weiner
2017-01-26 1:47 ` Minchan Kim
2017-01-26 10:19 ` Mel Gorman
2017-01-26 20:07 ` Johannes Weiner
2017-01-26 20:58 ` Mel Gorman
2017-01-26 13:52 ` Michal Hocko
2017-01-26 5:44 ` [PATCH 0/5] mm: vmscan: fix kswapd writeback regression Hillf Danton
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