From: Wu Fengguang <fengguang.wu@intel.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Jan Kara <jack@suse.cz>, Christoph Hellwig <hch@lst.de>,
Dave Chinner <david@fromorbit.com>,
Greg Thelen <gthelen@google.com>,
Minchan Kim <minchan.kim@gmail.com>,
Vivek Goyal <vgoyal@redhat.com>,
Andrea Righi <arighi@develer.com>, linux-mm <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 10/18] writeback: dirty position control - bdi reserve area
Date: Sun, 18 Sep 2011 22:37:21 +0800 [thread overview]
Message-ID: <20110918143721.GA17240@localhost> (raw)
In-Reply-To: <20110918141705.GB15366@localhost>
On Sun, Sep 18, 2011 at 10:17:05PM +0800, Wu Fengguang wrote:
> On Mon, Sep 12, 2011 at 06:19:38PM +0800, Peter Zijlstra wrote:
> > On Wed, 2011-09-07 at 20:31 +0800, Wu Fengguang wrote:
> > > > > + x_intercept = min(write_bw, freerun);
> > > > > + if (bdi_dirty < x_intercept) {
> > > >
> > > > So the point of the freerun point is that we never throttle before it,
> > > > so basically all the below shouldn't be needed at all, right?
> > >
> > > Yes!
> > >
> > > > > + if (bdi_dirty > x_intercept / 8) {
> > > > > + pos_ratio *= x_intercept;
> > > > > + do_div(pos_ratio, bdi_dirty);
> > > > > + } else
> > > > > + pos_ratio *= 8;
> > > > > + }
> > > > > +
> > > > > return pos_ratio;
> > > > > }
> >
> > Does that mean we can remove this whole block?
>
> Right, if the bdi freerun concept is proved to work fine.
>
> Unfortunately I find it mostly yields lower performance than bdi
> reserve area. Patch is attached. If you would like me try other
> patches, I can easily kick off new tests and redo the comparison.
>
> Here is the nr_written numbers over various JBOD test cases,
> the larger, the better:
>
> bdi-reserve bdi-freerun diff case
> ---------------------------------------------------------------------------------------
> 38375271 31553807 -17.8% JBOD-10HDD-6G/xfs-100dd-1M-16p-5895M-20
> 30478879 28631491 -6.1% JBOD-10HDD-6G/xfs-10dd-1M-16p-5895M-20
> 29735407 28871956 -2.9% JBOD-10HDD-6G/xfs-1dd-1M-16p-5895M-20
> 30850350 28344165 -8.1% JBOD-10HDD-6G/xfs-2dd-1M-16p-5895M-20
> 17706200 16174684 -8.6% JBOD-10HDD-thresh=100M/xfs-100dd-1M-16p-5895M-100M
> 23374918 14376942 -38.5% JBOD-10HDD-thresh=100M/xfs-10dd-1M-16p-5895M-100M
> 20659278 19640375 -4.9% JBOD-10HDD-thresh=100M/xfs-1dd-1M-16p-5895M-100M
> 22517497 14552321 -35.4% JBOD-10HDD-thresh=100M/xfs-2dd-1M-16p-5895M-100M
> 68287850 61078553 -10.6% JBOD-10HDD-thresh=2G/xfs-100dd-1M-16p-5895M-2048M
> 33835247 32018425 -5.4% JBOD-10HDD-thresh=2G/xfs-10dd-1M-16p-5895M-2048M
> 30187817 29942083 -0.8% JBOD-10HDD-thresh=2G/xfs-1dd-1M-16p-5895M-2048M
> 30563144 30204022 -1.2% JBOD-10HDD-thresh=2G/xfs-2dd-1M-16p-5895M-2048M
> 34476862 34645398 +0.5% JBOD-10HDD-thresh=4G/xfs-10dd-1M-16p-5895M-4096M
> 30326479 30097263 -0.8% JBOD-10HDD-thresh=4G/xfs-1dd-1M-16p-5895M-4096M
> 30446767 30339683 -0.4% JBOD-10HDD-thresh=4G/xfs-2dd-1M-16p-5895M-4096M
> 40793956 45936678 +12.6% JBOD-10HDD-thresh=800M/xfs-100dd-1M-16p-5895M-800M
> 27481305 24867282 -9.5% JBOD-10HDD-thresh=800M/xfs-10dd-1M-16p-5895M-800M
> 25651257 22507406 -12.3% JBOD-10HDD-thresh=800M/xfs-1dd-1M-16p-5895M-800M
> 19849350 21298787 +7.3% JBOD-10HDD-thresh=800M/xfs-2dd-1M-16p-5895M-800M
BTW, I also compared the IO-less patchset and the vanilla kernel's
JBOD performance. Basically, the performance is lightly improved
under large memory, and reduced a lot in small memory servers.
vanillla IO-less
--------------------------------------------------------------------------------
31189025 34476862 +10.5% JBOD-10HDD-thresh=4G/xfs-10dd-1M-16p-5895M-4096M
30441974 30326479 -0.4% JBOD-10HDD-thresh=4G/xfs-1dd-1M-16p-5895M-4096M
30484578 30446767 -0.1% JBOD-10HDD-thresh=4G/xfs-2dd-1M-16p-5895M-4096M
68532421 68287850 -0.4% JBOD-10HDD-thresh=2G/xfs-100dd-1M-16p-5895M-2048M
31606793 33835247 +7.1% JBOD-10HDD-thresh=2G/xfs-10dd-1M-16p-5895M-2048M
30404955 30187817 -0.7% JBOD-10HDD-thresh=2G/xfs-1dd-1M-16p-5895M-2048M
30425591 30563144 +0.5% JBOD-10HDD-thresh=2G/xfs-2dd-1M-16p-5895M-2048M
40451069 38375271 -5.1% JBOD-10HDD-6G/xfs-100dd-1M-16p-5895M-20
30903629 30478879 -1.4% JBOD-10HDD-6G/xfs-10dd-1M-16p-5895M-20
30113560 29735407 -1.3% JBOD-10HDD-6G/xfs-1dd-1M-16p-5895M-20
30181418 30850350 +2.2% JBOD-10HDD-6G/xfs-2dd-1M-16p-5895M-20
46067335 40793956 -11.4% JBOD-10HDD-thresh=800M/xfs-100dd-1M-16p-5895M-800M
30425063 27481305 -9.7% JBOD-10HDD-thresh=800M/xfs-10dd-1M-16p-5895M-800M
28437929 25651257 -9.8% JBOD-10HDD-thresh=800M/xfs-1dd-1M-16p-5895M-800M
29409406 19849350 -32.5% JBOD-10HDD-thresh=800M/xfs-2dd-1M-16p-5895M-800M
26508063 17706200 -33.2% JBOD-10HDD-thresh=100M/xfs-100dd-1M-16p-5895M-100M
23767810 23374918 -1.7% JBOD-10HDD-thresh=100M/xfs-10dd-1M-16p-5895M-100M
28032891 20659278 -26.3% JBOD-10HDD-thresh=100M/xfs-1dd-1M-16p-5895M-100M
26049973 22517497 -13.6% JBOD-10HDD-thresh=100M/xfs-2dd-1M-16p-5895M-100M
There are still some itches in JBOD..
Thanks,
Fengguang
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next prev parent reply other threads:[~2011-09-18 14:37 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-04 1:53 [PATCH 00/18] IO-less dirty throttling v11 Wu Fengguang
2011-09-04 1:53 ` [PATCH 01/18] writeback: account per-bdi accumulated dirtied pages Wu Fengguang
2011-09-04 1:53 ` [PATCH 02/18] writeback: dirty position control Wu Fengguang
2011-09-05 15:02 ` Peter Zijlstra
2011-09-06 2:10 ` Wu Fengguang
2011-09-05 15:05 ` Peter Zijlstra
2011-09-06 2:43 ` Wu Fengguang
2011-09-06 18:20 ` Vivek Goyal
2011-09-08 2:53 ` Wu Fengguang
2011-11-12 5:44 ` Nai Xia
2011-09-04 1:53 ` [PATCH 03/18] writeback: dirty rate control Wu Fengguang
2011-09-29 11:57 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 04/18] writeback: stabilize bdi->dirty_ratelimit Wu Fengguang
2011-09-04 1:53 ` [PATCH 05/18] writeback: per task dirty rate limit Wu Fengguang
2011-09-06 15:47 ` Peter Zijlstra
2011-09-06 23:27 ` Jan Kara
2011-09-06 23:34 ` Jan Kara
2011-09-07 7:27 ` Peter Zijlstra
2011-09-07 1:04 ` Wu Fengguang
2011-09-07 7:31 ` Peter Zijlstra
2011-09-07 11:00 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 06/18] writeback: IO-less balance_dirty_pages() Wu Fengguang
2011-09-06 12:13 ` Peter Zijlstra
2011-09-07 2:46 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 07/18] writeback: dirty ratelimit - think time compensation Wu Fengguang
2011-09-04 1:53 ` [PATCH 08/18] writeback: trace dirty_ratelimit Wu Fengguang
2011-09-04 1:53 ` [PATCH 09/18] writeback: trace balance_dirty_pages Wu Fengguang
2011-09-04 1:53 ` [PATCH 10/18] writeback: dirty position control - bdi reserve area Wu Fengguang
2011-09-06 14:09 ` Peter Zijlstra
2011-09-07 12:31 ` Wu Fengguang
2011-09-12 10:19 ` Peter Zijlstra
2011-09-18 14:17 ` Wu Fengguang
2011-09-18 14:37 ` Wu Fengguang [this message]
2011-09-18 14:47 ` Wu Fengguang
2011-09-28 14:02 ` Wu Fengguang
2011-09-28 14:50 ` Peter Zijlstra
2011-09-29 3:32 ` Wu Fengguang
2011-09-29 8:49 ` Peter Zijlstra
2011-09-29 11:05 ` Wu Fengguang
2011-09-29 12:15 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 11/18] block: add bdi flag to indicate risk of io queue underrun Wu Fengguang
2011-09-06 14:22 ` Peter Zijlstra
2011-09-07 2:37 ` Wu Fengguang
2011-09-07 7:31 ` Peter Zijlstra
2011-09-04 1:53 ` [PATCH 12/18] writeback: balanced_rate cannot exceed write bandwidth Wu Fengguang
2011-09-04 1:53 ` [PATCH 13/18] writeback: limit max dirty pause time Wu Fengguang
2011-09-06 14:52 ` Peter Zijlstra
2011-09-07 2:35 ` Wu Fengguang
2011-09-12 10:22 ` Peter Zijlstra
2011-09-18 14:23 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 14/18] writeback: control " Wu Fengguang
2011-09-06 15:51 ` Peter Zijlstra
2011-09-07 2:02 ` Wu Fengguang
2011-09-12 10:28 ` Peter Zijlstra
2011-09-04 1:53 ` [PATCH 15/18] writeback: charge leaked page dirties to active tasks Wu Fengguang
2011-09-06 16:16 ` Peter Zijlstra
2011-09-07 9:06 ` Wu Fengguang
2011-09-07 0:17 ` Jan Kara
2011-09-07 9:37 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 16/18] writeback: fix dirtied pages accounting on sub-page writes Wu Fengguang
2011-09-04 1:53 ` [PATCH 17/18] writeback: fix dirtied pages accounting on redirty Wu Fengguang
2011-09-06 16:18 ` Peter Zijlstra
2011-09-07 0:22 ` Jan Kara
2011-09-07 1:18 ` Wu Fengguang
2011-09-07 6:56 ` Christoph Hellwig
2011-09-07 8:19 ` Peter Zijlstra
2011-09-07 16:42 ` Jan Kara
2011-09-07 16:46 ` Christoph Hellwig
2011-09-08 8:51 ` Steven Whitehouse
2011-09-04 1:53 ` [PATCH 18/18] btrfs: fix dirtied pages accounting on sub-page writes Wu Fengguang
2011-09-07 13:32 ` [PATCH 00/18] IO-less dirty throttling v11 Wu Fengguang
2011-09-07 19:14 ` Trond Myklebust
2011-09-28 14:58 ` Christoph Hellwig
2011-09-29 4:11 ` Wu Fengguang
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