From: Andi Kleen <andi@firstfloor.org>
To: john stultz <johnstul@us.ibm.com>
Cc: linux-ext4@vger.kernel.org, Mingming Cao <cmm@us.ibm.com>,
keith maanthey <kmannth@us.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>,
"Theodore Ts'o" <tytso@mit.edu>, Darren Hart <dvhltc@us.ibm.com>,
tim.c.chen@intel.com
Subject: Re: ext4 dbench performance with CONFIG_PREEMPT_RT
Date: Fri, 09 Apr 2010 17:49:54 +0200 [thread overview]
Message-ID: <87d3y8wrq5.fsf@basil.nowhere.org> (raw)
In-Reply-To: <1270682478.3755.58.camel@localhost.localdomain> (john stultz's message of "Wed, 07 Apr 2010 16:21:18 -0700")
john stultz <johnstul@us.ibm.com> writes:
>
> Further using lockstat I was able to isolate it the contention down to
> the journal j_state_lock, and then adding some lock owner tracking, I
> was able to see that the lock owners were almost always in
> start_this_handle, and jbd2_journal_stop when we saw contention (with
> the freq breakdown being about 55% in jbd2_journal_stop and 45% in
> start_this_handle).
FWIW we've been also seeing this on larger systems without RT.
The journal locks are the number one contention in some workloads.
So it's not just a RT problem.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2010-04-09 15:50 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-07 23:21 ext4 dbench performance with CONFIG_PREEMPT_RT john stultz
2010-04-08 3:46 ` tytso
2010-04-08 10:18 ` Theodore Tso
2010-04-08 20:41 ` john stultz
2010-04-08 21:10 ` tytso
2010-04-13 3:52 ` john stultz
2010-04-14 3:04 ` john stultz
2010-04-08 22:37 ` Mingming Cao
2010-04-12 19:46 ` Jan Kara
2010-04-13 14:52 ` tytso
2010-04-13 16:25 ` Darren Hart
2010-06-02 22:35 ` j_state_lock patch data (was: Re: ext4 dbench performance with CONFIG_PREEMPT_RT) Eric Whitney
2010-04-09 15:49 ` Andi Kleen [this message]
2010-04-09 23:33 ` ext4 dbench performance with CONFIG_PREEMPT_RT tytso
2010-04-09 23:48 ` Chen, Tim C
2010-04-09 23:57 ` john stultz
2010-04-10 11:58 ` tytso
2010-04-12 19:54 ` Chen, Tim C
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