From: Ted Ts'o <tytso@mit.edu>
To: john stultz <johnstul@us.ibm.com>
Cc: Ext4 Developers List <linux-ext4@vger.kernel.org>,
Keith Maanthey <kmannth@us.ibm.com>,
Eric Whitney <eric.whitney@hp.com>
Subject: Re: [PATCH] jbd2: Use atomic variables to avoid taking t_handle_lock in jbd2_journal_stop
Date: Mon, 2 Aug 2010 20:06:09 -0400 [thread overview]
Message-ID: <20100803000609.GI25653@thunk.org> (raw)
In-Reply-To: <1280790152.3966.14.camel@localhost.localdomain>
On Mon, Aug 02, 2010 at 04:02:32PM -0700, john stultz wrote:
> >From these numbers, it looks like the atomic variables are a minor
> improvement for -rt, but the improvement isn't as drastic as the earlier
> j_state lock change, or the vfs scalability patchset.
Thanks for doing this quick test run! I was expecting to see a more
dramatic difference, since the j_state_lock patch removed one of the
two global locks in jbd2_journal_stop, and the t_handle_lock patch
removed the second of the two global locks. But I guess the
j_state_lock contention in start_this_handle() is still the dominating factor.
It's interesting that apparently the latest t_handle_lock patch
doesn't seem to make much difference unless the VFS scalability patch
is also applied. I'm not sure why that makes a difference, but it's
nice to know that with the VFS scalability patch it does seem to help,
even if it doesn't help as much as I had hoped.
OK, I guess we'll have to start working on the more aggressive
scalability fix ups....
- Ted
next prev parent reply other threads:[~2010-08-03 0:06 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-02 12:48 [PATCH] jbd2: Use atomic variables to avoid taking t_handle_lock in jbd2_journal_stop Theodore Ts'o
2010-08-02 23:02 ` john stultz
2010-08-03 0:06 ` Ted Ts'o [this message]
2010-08-03 0:53 ` john stultz
2010-08-03 2:52 ` john stultz
2010-08-03 16:06 ` Ted Ts'o
2010-08-03 19:22 ` Eric Whitney
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