public inbox for linux-xfs@vger.kernel.org
 help / color / mirror / Atom feed
From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH 08/12] xfs: convert l_tail_lsn to an atomic variable.
Date: Mon, 20 Dec 2010 07:06:34 -0500	[thread overview]
Message-ID: <20101220120634.GA3582@infradead.org> (raw)
In-Reply-To: <1292215483-18224-9-git-send-email-david@fromorbit.com>

On Mon, Dec 13, 2010 at 03:44:39PM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
> 
> log->l_tail_lsn is currently protected by the log grant lock. The
> lock is only needed for serialising readers against writers, so we
> don't really need the lock if we make the l_tail_lsn variable an
> atomic. Converting the l_tail_lsn variable to an atomic64_t means we
> can start to peel back the grant lock from various operations.
> 
> Also, provide functions to safely crack an atomic LSN variable into
> it's component pieces and to recombined the components into an
> atomic variable. Use them where appropriate.
> 
> This also removes the need for explicitly holding a spinlock to read
> the l_tail_lsn on 32 bit platforms.

I know I suggested this, but I think the atomic read of l_tail_lsn
in xlog_space_left might be problemetic for the call from
xlog_grant_push_ail, where we read it twice now.  Maybe split
xlog_space_left into a __xlog_space_left that gets the already cracked
values, and xlog_space_left as a wrapper around it?

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs

  reply	other threads:[~2010-12-20 12:04 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-12-13  4:44 xfs: grant lock scaling and removal V3 Dave Chinner
2010-12-13  4:44 ` [PATCH 01/12] xfs: convert log grant ticket queues to list heads Dave Chinner
2010-12-20 11:34   ` Christoph Hellwig
2010-12-21  0:55     ` Dave Chinner
2010-12-13  4:44 ` [PATCH 02/12] xfs: fact out common grant head/log tail verification code Dave Chinner
2010-12-20 11:51   ` Christoph Hellwig
2010-12-13  4:44 ` [PATCH 03/12] xfs: rework log grant space calculations Dave Chinner
2010-12-20 11:37   ` Christoph Hellwig
2010-12-13  4:44 ` [PATCH 04/12] xfs: combine grant heads into a single 64 bit integer Dave Chinner
2010-12-20 11:40   ` Christoph Hellwig
2010-12-13  4:44 ` [PATCH 05/12] xfs: use wait queues directly for the log wait queues Dave Chinner
2010-12-20 11:40   ` Christoph Hellwig
2010-12-13  4:44 ` [PATCH 06/12] xfs: make AIL tail pushing independent of the grant lock Dave Chinner
2010-12-20 11:41   ` Christoph Hellwig
2010-12-13  4:44 ` [PATCH 07/12] xfs: convert l_last_sync_lsn to an atomic variable Dave Chinner
2010-12-13  4:44 ` [PATCH 08/12] xfs: convert l_tail_lsn " Dave Chinner
2010-12-20 12:06   ` Christoph Hellwig [this message]
2010-12-21  1:27     ` Dave Chinner
2010-12-13  4:44 ` [PATCH 09/12] xfs: convert log grant heads to atomic variables Dave Chinner
2010-12-13  4:44 ` [PATCH 10/12] xfs: introduce new locks for the log grant ticket wait queues Dave Chinner
2010-12-20 11:49   ` Christoph Hellwig
2010-12-13  4:44 ` [PATCH 11/12] xfs: convert grant head manipulations to lockless algorithm Dave Chinner
2010-12-20 11:50   ` Christoph Hellwig
2010-12-13  4:44 ` [PATCH 12/12] xfs: kill useless spinlock_destroy macro Dave Chinner

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20101220120634.GA3582@infradead.org \
    --to=hch@infradead.org \
    --cc=david@fromorbit.com \
    --cc=xfs@oss.sgi.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox