From: Andrew Morton <akpm@linux-foundation.org>
To: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>, Jan Kara <jack@suse.cz>,
LKML <linux-kernel@vger.kernel.org>, XFS <xfs@oss.sgi.com>,
Christoph Hellwig <hch@infradead.org>,
Linux-MM <linux-mm@kvack.org>,
Minchan Kim <minchan.kim@gmail.com>,
Wu Fengguang <fengguang.wu@intel.com>,
Johannes Weiner <jweiner@redhat.com>
Subject: Re: [PATCH 6/7] mm: vmscan: Throttle reclaim if encountering too many dirty pages under writeback
Date: Thu, 18 Aug 2011 16:54:28 -0700 [thread overview]
Message-ID: <20110818165428.4f01a1b9.akpm@linux-foundation.org> (raw)
In-Reply-To: <1312973240-32576-7-git-send-email-mgorman@suse.de>
On Wed, 10 Aug 2011 11:47:19 +0100
Mel Gorman <mgorman@suse.de> wrote:
> The percentage that must be in writeback depends on the priority. At
> default priority, all of them must be dirty. At DEF_PRIORITY-1, 50%
> of them must be, DEF_PRIORITY-2, 25% etc. i.e. as pressure increases
> the greater the likelihood the process will get throttled to allow
> the flusher threads to make some progress.
It'd be nice if the code comment were to capture this piece of implicit
arithmetic. After all, it's a magic number and magic numbers should
stick out like sore thumbs.
And.. how do we know that the chosen magic numbers were optimal?
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WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm@linux-foundation.org>
To: Mel Gorman <mgorman@suse.de>
Cc: Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>, XFS <xfs@oss.sgi.com>,
Dave Chinner <david@fromorbit.com>,
Christoph Hellwig <hch@infradead.org>,
Johannes Weiner <jweiner@redhat.com>,
Wu Fengguang <fengguang.wu@intel.com>, Jan Kara <jack@suse.cz>,
Rik van Riel <riel@redhat.com>,
Minchan Kim <minchan.kim@gmail.com>
Subject: Re: [PATCH 6/7] mm: vmscan: Throttle reclaim if encountering too many dirty pages under writeback
Date: Thu, 18 Aug 2011 16:54:28 -0700 [thread overview]
Message-ID: <20110818165428.4f01a1b9.akpm@linux-foundation.org> (raw)
In-Reply-To: <1312973240-32576-7-git-send-email-mgorman@suse.de>
On Wed, 10 Aug 2011 11:47:19 +0100
Mel Gorman <mgorman@suse.de> wrote:
> The percentage that must be in writeback depends on the priority. At
> default priority, all of them must be dirty. At DEF_PRIORITY-1, 50%
> of them must be, DEF_PRIORITY-2, 25% etc. i.e. as pressure increases
> the greater the likelihood the process will get throttled to allow
> the flusher threads to make some progress.
It'd be nice if the code comment were to capture this piece of implicit
arithmetic. After all, it's a magic number and magic numbers should
stick out like sore thumbs.
And.. how do we know that the chosen magic numbers were optimal?
WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm@linux-foundation.org>
To: Mel Gorman <mgorman@suse.de>
Cc: Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>, XFS <xfs@oss.sgi.com>,
Dave Chinner <david@fromorbit.com>,
Christoph Hellwig <hch@infradead.org>,
Johannes Weiner <jweiner@redhat.com>,
Wu Fengguang <fengguang.wu@intel.com>, Jan Kara <jack@suse.cz>,
Rik van Riel <riel@redhat.com>,
Minchan Kim <minchan.kim@gmail.com>
Subject: Re: [PATCH 6/7] mm: vmscan: Throttle reclaim if encountering too many dirty pages under writeback
Date: Thu, 18 Aug 2011 16:54:28 -0700 [thread overview]
Message-ID: <20110818165428.4f01a1b9.akpm@linux-foundation.org> (raw)
In-Reply-To: <1312973240-32576-7-git-send-email-mgorman@suse.de>
On Wed, 10 Aug 2011 11:47:19 +0100
Mel Gorman <mgorman@suse.de> wrote:
> The percentage that must be in writeback depends on the priority. At
> default priority, all of them must be dirty. At DEF_PRIORITY-1, 50%
> of them must be, DEF_PRIORITY-2, 25% etc. i.e. as pressure increases
> the greater the likelihood the process will get throttled to allow
> the flusher threads to make some progress.
It'd be nice if the code comment were to capture this piece of implicit
arithmetic. After all, it's a magic number and magic numbers should
stick out like sore thumbs.
And.. how do we know that the chosen magic numbers were optimal?
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next prev parent reply other threads:[~2011-08-18 23:55 UTC|newest]
Thread overview: 120+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-10 10:47 [PATCH 0/7] Reduce filesystem writeback from page reclaim v3 Mel Gorman
2011-08-10 10:47 ` Mel Gorman
2011-08-10 10:47 ` Mel Gorman
2011-08-10 10:47 ` [PATCH 1/7] mm: vmscan: Do not writeback filesystem pages in direct reclaim Mel Gorman
2011-08-10 10:47 ` Mel Gorman
2011-08-10 10:47 ` Mel Gorman
2011-08-10 12:40 ` Johannes Weiner
2011-08-10 12:40 ` Johannes Weiner
2011-08-10 12:40 ` Johannes Weiner
2011-08-11 9:03 ` KAMEZAWA Hiroyuki
2011-08-11 9:03 ` KAMEZAWA Hiroyuki
2011-08-11 9:03 ` KAMEZAWA Hiroyuki
2011-08-11 15:57 ` Rik van Riel
2011-08-11 15:57 ` Rik van Riel
2011-08-11 15:57 ` Rik van Riel
2011-08-10 10:47 ` [PATCH 2/7] mm: vmscan: Remove dead code related to lumpy reclaim waiting on pages under writeback Mel Gorman
2011-08-10 10:47 ` Mel Gorman
2011-08-10 10:47 ` Mel Gorman
2011-08-10 12:41 ` Johannes Weiner
2011-08-10 12:41 ` Johannes Weiner
2011-08-10 12:41 ` Johannes Weiner
2011-08-10 23:19 ` Minchan Kim
2011-08-10 23:19 ` Minchan Kim
2011-08-10 23:19 ` Minchan Kim
2011-08-11 9:05 ` KAMEZAWA Hiroyuki
2011-08-11 9:05 ` KAMEZAWA Hiroyuki
2011-08-11 9:05 ` KAMEZAWA Hiroyuki
2011-08-11 16:52 ` Rik van Riel
2011-08-11 16:52 ` Rik van Riel
2011-08-11 16:52 ` Rik van Riel
2011-08-10 10:47 ` [PATCH 3/7] xfs: Warn if direct reclaim tries to writeback pages Mel Gorman
2011-08-10 10:47 ` Mel Gorman
2011-08-10 10:47 ` Mel Gorman
2011-08-11 16:53 ` Rik van Riel
2011-08-11 16:53 ` Rik van Riel
2011-08-11 16:53 ` Rik van Riel
2011-08-10 10:47 ` [PATCH 4/7] ext4: " Mel Gorman
2011-08-10 10:47 ` Mel Gorman
2011-08-10 10:47 ` Mel Gorman
2011-08-11 17:07 ` Rik van Riel
2011-08-11 17:07 ` Rik van Riel
2011-08-11 17:07 ` Rik van Riel
2011-08-10 10:47 ` [PATCH 5/7] mm: vmscan: Do not writeback filesystem pages in kswapd except in high priority Mel Gorman
2011-08-10 10:47 ` Mel Gorman
2011-08-10 10:47 ` Mel Gorman
2011-08-10 12:44 ` Johannes Weiner
2011-08-10 12:44 ` Johannes Weiner
2011-08-10 12:44 ` Johannes Weiner
2011-08-11 9:10 ` KAMEZAWA Hiroyuki
2011-08-11 9:10 ` KAMEZAWA Hiroyuki
2011-08-11 9:10 ` KAMEZAWA Hiroyuki
2011-08-11 20:25 ` Mel Gorman
2011-08-11 20:25 ` Mel Gorman
2011-08-11 20:25 ` Mel Gorman
2011-08-17 1:06 ` KAMEZAWA Hiroyuki
2011-08-17 1:06 ` KAMEZAWA Hiroyuki
2011-08-17 1:06 ` KAMEZAWA Hiroyuki
2011-08-11 18:18 ` Rik van Riel
2011-08-11 18:18 ` Rik van Riel
2011-08-11 18:18 ` Rik van Riel
2011-08-11 20:38 ` Mel Gorman
2011-08-11 20:38 ` Mel Gorman
2011-08-11 20:38 ` Mel Gorman
2011-08-10 10:47 ` [PATCH 6/7] mm: vmscan: Throttle reclaim if encountering too many dirty pages under writeback Mel Gorman
2011-08-10 10:47 ` Mel Gorman
2011-08-10 10:47 ` Mel Gorman
2011-08-11 9:18 ` KAMEZAWA Hiroyuki
2011-08-11 9:18 ` KAMEZAWA Hiroyuki
2011-08-11 9:18 ` KAMEZAWA Hiroyuki
2011-08-12 2:47 ` Rik van Riel
2011-08-12 2:47 ` Rik van Riel
2011-08-12 2:47 ` Rik van Riel
2011-08-16 14:06 ` Wu Fengguang
2011-08-16 14:06 ` Wu Fengguang
2011-08-16 14:06 ` Wu Fengguang
2011-08-16 15:02 ` Mel Gorman
2011-08-16 15:02 ` Mel Gorman
2011-08-16 15:02 ` Mel Gorman
2011-08-18 14:02 ` Wu Fengguang
2011-08-18 14:02 ` Wu Fengguang
2011-08-18 14:02 ` Wu Fengguang
2011-08-18 23:54 ` Andrew Morton [this message]
2011-08-18 23:54 ` Andrew Morton
2011-08-18 23:54 ` Andrew Morton
2011-08-30 13:49 ` Mel Gorman
2011-08-30 13:49 ` Mel Gorman
2011-08-30 13:49 ` Mel Gorman
2011-08-31 9:53 ` Mel Gorman
2011-08-31 9:53 ` Mel Gorman
2011-08-31 9:53 ` Mel Gorman
2011-08-10 10:47 ` [PATCH 7/7] mm: vmscan: Immediately reclaim end-of-LRU dirty pages when writeback completes Mel Gorman
2011-08-10 10:47 ` Mel Gorman
2011-08-10 10:47 ` Mel Gorman
2011-08-10 23:22 ` Minchan Kim
2011-08-10 23:22 ` Minchan Kim
2011-08-10 23:22 ` Minchan Kim
2011-08-11 9:19 ` KAMEZAWA Hiroyuki
2011-08-11 9:19 ` KAMEZAWA Hiroyuki
2011-08-11 9:19 ` KAMEZAWA Hiroyuki
2011-08-12 15:27 ` Rik van Riel
2011-08-12 15:27 ` Rik van Riel
2011-08-12 15:27 ` Rik van Riel
2011-08-10 11:00 ` [PATCH 0/7] Reduce filesystem writeback from page reclaim v3 Christoph Hellwig
2011-08-10 11:00 ` Christoph Hellwig
2011-08-10 11:00 ` Christoph Hellwig
2011-08-10 11:15 ` Mel Gorman
2011-08-10 11:15 ` Mel Gorman
2011-08-10 11:15 ` Mel Gorman
2011-08-11 23:45 ` Christoph Hellwig
2011-08-11 23:45 ` Christoph Hellwig
2011-08-11 23:45 ` Christoph Hellwig
2011-08-18 23:54 ` Andrew Morton
2011-08-18 23:54 ` Andrew Morton
2011-08-18 23:54 ` Andrew Morton
2011-08-20 19:33 ` Mel Gorman
2011-08-20 19:33 ` Mel Gorman
2011-08-20 19:33 ` Mel Gorman
2011-08-30 13:19 ` Mel Gorman
2011-08-30 13:19 ` Mel Gorman
2011-08-30 13:19 ` Mel Gorman
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