linux-ext4 - Re: High CPU Utilization When Copying to Ext4

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Message-ID: <m27h7sd742.fsf@firstfloor.org>
Date:	Fri, 08 Jul 2011 10:17:49 -0700
From:	Andi Kleen <andi@...stfloor.org>
To:	Sean McCauliff <Sean.D.McCauliff@...a.gov>
Cc:	"Ted Ts'o" <tytso@....edu>,
	"linux-ext4\@vger.kernel.org" <linux-ext4@...r.kernel.org>
Subject: Re: High CPU Utilization When Copying to Ext4

Sean McCauliff <Sean.D.McCauliff@...a.gov> writes:

> I tried running perf on the copy program on subset of the sparse
> files. It seems like ext4 is the source of high cpu utilization.  At
> this point this high cpu utilization is very annoying, but I can live
> with this problem.  If you know something simple I could do to
> alleviate this problem I would be most appreciative.  At the end of
> this email is a consolidation of information about this problem.
>
> Events: 6M cycles
> -76.80%     java  [kernel.kallsyms]      [k] ext4_mb_good_group
>   - ext4_mb_good_group

Is your file system too full?

A lot of file system get inefficient in allocating blocks when the 
file system is nearly full.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only
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