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>,
Tejun Heo <tj@kernel.org>, Jens Axboe <axboe@kernel.dk>,
"Li, Shaohua" <shaohua.li@intel.com>,
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 11/18] block: add bdi flag to indicate risk of io queue underrun
Date: Wed, 7 Sep 2011 10:37:19 +0800 [thread overview]
Message-ID: <20110907023719.GC13755@localhost> (raw)
In-Reply-To: <1315318968.14232.6.camel@twins>
On Tue, Sep 06, 2011 at 10:22:48PM +0800, Peter Zijlstra wrote:
> On Sun, 2011-09-04 at 09:53 +0800, Wu Fengguang wrote:
> > +++ linux-next/mm/page-writeback.c 2011-08-31 14:40:58.000000000 +0800
> > @@ -1067,6 +1067,9 @@ static void balance_dirty_pages(struct a
> > nr_dirty, bdi_thresh, bdi_dirty,
> > start_time);
> >
> > + if (unlikely(!dirty_exceeded && bdi_async_underrun(bdi)))
> > + break;
> > +
> > dirty_ratelimit = bdi->dirty_ratelimit;
> > pos_ratio = bdi_position_ratio(bdi, dirty_thresh,
> > background_thresh, nr_dirty,
>
> So dirty_exceeded looks like:
>
>
> 1109 dirty_exceeded = (bdi_dirty > bdi_thresh) ||
> 1110 (nr_dirty > dirty_thresh);
>
> Would it make sense to write it as:
>
> if (nr_dirty > dirty_thresh ||
> (nr_dirty > freerun && bdi_dirty > bdi_thresh))
> dirty_exceeded = 1;
>
> So that we don't actually throttle bdi thingies when we're still in the
> freerun area?
Sounds not necessary -- (nr_dirty > freerun) is implicitly true
because there is a big break early in the loop:
if (nr_dirty > freerun)
break;
Thanks,
Fengguang
WARNING: multiple messages have this Message-ID (diff)
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>,
Tejun Heo <tj@kernel.org>, Jens Axboe <axboe@kernel.dk>,
"Li, Shaohua" <shaohua.li@intel.com>,
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 11/18] block: add bdi flag to indicate risk of io queue underrun
Date: Wed, 7 Sep 2011 10:37:19 +0800 [thread overview]
Message-ID: <20110907023719.GC13755@localhost> (raw)
In-Reply-To: <1315318968.14232.6.camel@twins>
On Tue, Sep 06, 2011 at 10:22:48PM +0800, Peter Zijlstra wrote:
> On Sun, 2011-09-04 at 09:53 +0800, Wu Fengguang wrote:
> > +++ linux-next/mm/page-writeback.c 2011-08-31 14:40:58.000000000 +0800
> > @@ -1067,6 +1067,9 @@ static void balance_dirty_pages(struct a
> > nr_dirty, bdi_thresh, bdi_dirty,
> > start_time);
> >
> > + if (unlikely(!dirty_exceeded && bdi_async_underrun(bdi)))
> > + break;
> > +
> > dirty_ratelimit = bdi->dirty_ratelimit;
> > pos_ratio = bdi_position_ratio(bdi, dirty_thresh,
> > background_thresh, nr_dirty,
>
> So dirty_exceeded looks like:
>
>
> 1109 dirty_exceeded = (bdi_dirty > bdi_thresh) ||
> 1110 (nr_dirty > dirty_thresh);
>
> Would it make sense to write it as:
>
> if (nr_dirty > dirty_thresh ||
> (nr_dirty > freerun && bdi_dirty > bdi_thresh))
> dirty_exceeded = 1;
>
> So that we don't actually throttle bdi thingies when we're still in the
> freerun area?
Sounds not necessary -- (nr_dirty > freerun) is implicitly true
because there is a big break early in the loop:
if (nr_dirty > freerun)
break;
Thanks,
Fengguang
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next prev parent reply other threads:[~2011-09-07 2:37 UTC|newest]
Thread overview: 175+ 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 ` Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 01/18] writeback: account per-bdi accumulated dirtied pages Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 02/18] writeback: dirty position control Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-05 15:02 ` Peter Zijlstra
2011-09-05 15:02 ` Peter Zijlstra
2011-09-06 2:10 ` Wu Fengguang
2011-09-06 2:10 ` Wu Fengguang
2011-09-05 15:05 ` Peter Zijlstra
2011-09-05 15:05 ` Peter Zijlstra
2011-09-06 2:43 ` Wu Fengguang
2011-09-06 2:43 ` Wu Fengguang
2011-09-06 18:20 ` Vivek Goyal
2011-09-06 18:20 ` Vivek Goyal
2011-09-08 2:53 ` Wu Fengguang
2011-09-08 2:53 ` Wu Fengguang
2011-11-12 5:44 ` Nai Xia
2011-11-12 5:44 ` Nai Xia
2011-09-04 1:53 ` [PATCH 03/18] writeback: dirty rate control Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-29 11:57 ` 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 ` Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 05/18] writeback: per task dirty rate limit Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-06 15:47 ` Peter Zijlstra
2011-09-06 15:47 ` Peter Zijlstra
2011-09-06 15:47 ` Peter Zijlstra
2011-09-06 23:27 ` Jan Kara
2011-09-06 23:27 ` Jan Kara
2011-09-06 23:34 ` Jan Kara
2011-09-06 23:34 ` Jan Kara
2011-09-07 7:27 ` Peter Zijlstra
2011-09-07 7:27 ` Peter Zijlstra
2011-09-07 7:27 ` Peter Zijlstra
2011-09-07 1:04 ` Wu Fengguang
2011-09-07 1:04 ` Wu Fengguang
2011-09-07 7:31 ` Peter Zijlstra
2011-09-07 7:31 ` Peter Zijlstra
2011-09-07 7:31 ` Peter Zijlstra
2011-09-07 11:00 ` Wu Fengguang
2011-09-07 11:00 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 06/18] writeback: IO-less balance_dirty_pages() Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-06 12:13 ` Peter Zijlstra
2011-09-06 12:13 ` Peter Zijlstra
2011-09-06 12:13 ` Peter Zijlstra
2011-09-07 2:46 ` Wu Fengguang
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 ` Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 08/18] writeback: trace dirty_ratelimit Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 09/18] writeback: trace balance_dirty_pages Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 10/18] writeback: dirty position control - bdi reserve area Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-06 14:09 ` Peter Zijlstra
2011-09-06 14:09 ` Peter Zijlstra
2011-09-06 14:09 ` Peter Zijlstra
2011-09-07 12:31 ` Wu Fengguang
2011-09-07 12:31 ` Wu Fengguang
2011-09-12 10:19 ` Peter Zijlstra
2011-09-12 10:19 ` Peter Zijlstra
2011-09-12 10:19 ` Peter Zijlstra
2011-09-18 14:17 ` Wu Fengguang
2011-09-18 14:37 ` Wu Fengguang
2011-09-18 14:37 ` Wu Fengguang
2011-09-18 14:47 ` Wu Fengguang
2011-09-18 14:47 ` Wu Fengguang
2011-09-28 14:02 ` Wu Fengguang
2011-09-28 14:50 ` Peter Zijlstra
2011-09-28 14:50 ` Peter Zijlstra
2011-09-29 3:32 ` Wu Fengguang
2011-09-29 3:32 ` Wu Fengguang
2011-09-29 8:49 ` Peter Zijlstra
2011-09-29 8:49 ` Peter Zijlstra
2011-09-29 8:49 ` Peter Zijlstra
2011-09-29 11:05 ` Wu Fengguang
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
2011-09-04 1:53 ` Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-06 14:22 ` Peter Zijlstra
2011-09-06 14:22 ` Peter Zijlstra
2011-09-07 2:37 ` Wu Fengguang [this message]
2011-09-07 2:37 ` Wu Fengguang
2011-09-07 7:31 ` Peter Zijlstra
2011-09-07 7:31 ` Peter Zijlstra
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 ` Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 13/18] writeback: limit max dirty pause time Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-06 14:52 ` Peter Zijlstra
2011-09-06 14:52 ` Peter Zijlstra
2011-09-06 14:52 ` Peter Zijlstra
2011-09-07 2:35 ` Wu Fengguang
2011-09-07 2:35 ` Wu Fengguang
2011-09-12 10:22 ` Peter Zijlstra
2011-09-12 10:22 ` Peter Zijlstra
2011-09-12 10:22 ` Peter Zijlstra
2011-09-18 14:23 ` Wu Fengguang
2011-09-18 14:23 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 14/18] writeback: control " Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-06 15:51 ` Peter Zijlstra
2011-09-06 15:51 ` Peter Zijlstra
2011-09-06 15:51 ` Peter Zijlstra
2011-09-07 2:02 ` Wu Fengguang
2011-09-07 2:02 ` Wu Fengguang
2011-09-12 10:28 ` Peter Zijlstra
2011-09-12 10:28 ` Peter Zijlstra
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
2011-09-04 1:53 ` Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-06 16:16 ` Peter Zijlstra
2011-09-06 16:16 ` Peter Zijlstra
2011-09-06 16:16 ` Peter Zijlstra
2011-09-07 9:06 ` Wu Fengguang
2011-09-07 9:06 ` Wu Fengguang
2011-09-07 0:17 ` Jan Kara
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 ` Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 17/18] writeback: fix dirtied pages accounting on redirty Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-06 16:18 ` Peter Zijlstra
2011-09-06 16:18 ` Peter Zijlstra
2011-09-06 16:18 ` Peter Zijlstra
2011-09-07 0:22 ` Jan Kara
2011-09-07 0:22 ` Jan Kara
2011-09-07 1:18 ` Wu Fengguang
2011-09-07 6:56 ` Christoph Hellwig
2011-09-07 6:56 ` Christoph Hellwig
2011-09-07 8:19 ` Peter Zijlstra
2011-09-07 8:19 ` Peter Zijlstra
2011-09-07 8:19 ` Peter Zijlstra
2011-09-07 16:42 ` Jan Kara
2011-09-07 16:42 ` Jan Kara
2011-09-07 16:46 ` Christoph Hellwig
2011-09-07 16:46 ` Christoph Hellwig
2011-09-08 8:51 ` Steven Whitehouse
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
2011-09-04 1:53 ` Wu Fengguang
2011-09-04 1:53 ` Wu Fengguang
2011-09-07 13:32 ` [PATCH 00/18] IO-less dirty throttling v11 Wu Fengguang
2011-09-07 13:32 ` Wu Fengguang
2011-09-07 19:14 ` Trond Myklebust
2011-09-07 19:14 ` Trond Myklebust
2011-09-28 14:58 ` Christoph Hellwig
2011-09-28 14:58 ` Christoph Hellwig
2011-09-29 4:11 ` Wu Fengguang
2011-09-29 4:11 ` Wu Fengguang
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