linux-kernel - Re: [RT LATENCY] 249 microsecond latency caused by slub's unfreeze

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Message-ID: <1364316737.6345.192.camel@gandalf.local.home>
Date:	Tue, 26 Mar 2013 12:52:17 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Christoph Lameter <cl@...ux.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	RT <linux-rt-users@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Clark Williams <clark@...hat.com>
Subject: Re: [RT LATENCY] 249 microsecond latency caused by slub's
 unfreeze_partials() code.

On Mon, 2013-03-25 at 14:34 +0000, Christoph Lameter wrote:

> You can eliminate the whole thing by setting
> 
> /sys/kernel/slab/<whatever/cpu_partial
> 
> to zero.

Giving you an update.

I did the following:

# ls /sys/kernel/slab/*/cpu_partial | while read f; do
	echo 0 > $f
done


Then ran our test suite for 24 hours, and had a max latency of 135
microseconds. Well within our range for such a machine. Seems this is
definitely the cause of our latencies, as before, we would always
trigger a unacceptable latency within 12 hours.

Thanks for your help!

-- Steve


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