From: Dave Chinner <david@fromorbit.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH 5/6] xfs: convert the xfsaild threads to a workqueue
Date: Sun, 3 Apr 2011 10:38:47 +1000 [thread overview]
Message-ID: <20110403003847.GI6957@dastard> (raw)
In-Reply-To: <20110319134500.GB10056@infradead.org>
On Sat, Mar 19, 2011 at 09:45:00AM -0400, Christoph Hellwig wrote:
> On Fri, Mar 18, 2011 at 03:06:48PM +1100, Dave Chinner wrote:
> > It gets used by a second caller in the next patch that uses a
> > timeout of zero. The idea of adding a delay to a normal push is to
> > rate limit the number of times we do work so we always work on
> > batches rather a few items at a time in multiple executions of the
> > work.
> >
> > I'll see if it's simpler to just do this work directly in teh
> > callers, though.
>
> I don't think hiding this delay (uncommented) in the workqueue use is
> a good idea.
FWIW, we already have an implicit delay for frequent callers when
the AIL is busy - the uninterruptible sleep for sleeps of <= 20ms.
That was implemented specifically to rate-limit wakeups while the
xfsaild was busy pushing. This is essentially a different
implementation of the same mechanism.
> xlog_grant_push_ail has all the logics about when to push
> the AIL, so any batching should be grouped with that logic, and
> documented there. It in fact already has some comments static that
> a min/max watermark scheme would be useful.
Yes, it does, but that's a much bigger change that has some
potentially nasty problems like ensuring the watermarks are always a
sane distance apart which is difficult to do on small logs were a
single transaction reservation can easily be larger than 10% of the
log. Hence watermarks are a much harder change to validate and tune
compared to a simple push wakeup rate-limit...
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2011-04-03 0:35 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-10 0:05 [PATCH 0/6] xfs: Reduce OOM kill problems under heavy load V2 Dave Chinner
2011-03-10 0:05 ` [PATCH 1/6] xfs: introduce inode cluster buffer trylocks for xfs_iflush Dave Chinner
2011-03-10 17:31 ` Christoph Hellwig
2011-03-10 0:05 ` [PATCH 2/6] xfs: introduce a xfssyncd workqueue Dave Chinner
2011-03-10 17:34 ` Christoph Hellwig
2011-03-18 3:39 ` Dave Chinner
2011-03-10 0:05 ` [PATCH 3/6] xfs: convert ENOSPC inode flushing to use new syncd workqueue Dave Chinner
2011-03-10 17:35 ` Christoph Hellwig
2011-03-18 3:39 ` Dave Chinner
2011-03-10 0:05 ` [PATCH 4/6] xfs: introduce background inode reclaim work Dave Chinner
2011-03-10 17:40 ` Christoph Hellwig
2011-03-18 4:00 ` Dave Chinner
2011-03-10 0:05 ` [PATCH 5/6] xfs: convert the xfsaild threads to a workqueue Dave Chinner
2011-03-10 17:48 ` Christoph Hellwig
2011-03-18 4:06 ` Dave Chinner
2011-03-19 13:45 ` Christoph Hellwig
2011-04-03 0:38 ` Dave Chinner [this message]
2011-04-03 10:59 ` Christoph Hellwig
2011-04-04 2:11 ` Dave Chinner
2011-03-10 0:05 ` [PATCH 6/6] xfs: push the AIL from memory reclaim and periodic sync Dave Chinner
2011-03-10 21:31 ` Christoph Hellwig
2011-03-18 4:07 ` Dave Chinner
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