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Re: xfs - high CPU usage when removing files

To: Linux fs XFS <xfs@xxxxxxxxxxx>
Subject: Re: xfs - high CPU usage when removing files
From: Stefan Ring <stefanrin@xxxxxxxxx>
Date: Tue, 14 May 2013 13:11:02 +0200
Cc: Radoslaw Garbacz <radoslaw.garbacz@xxxxxxxxxxxxxxxxx>
Delivered-to: xfs@xxxxxxxxxxx
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In-reply-to: <20130514004751.GQ32675@dastard>
References: <CAHBw7oSxcTYEEFzzhpZfH_EshyYXOsRBpf=S+bLEgCyQZkLFsA@xxxxxxxxxxxxxx> <20130514004751.GQ32675@dastard>
>> I noticed a high CPU usage when removing files from XFS partition on Linux,
>> CentOS (always close to 100%).
>> Is it a known issue, or is it more likely to be attributed to my testing
>> methodology ('time' command)?
>
> If you are removing extremely fragmented files, then 100% CPU will
> be seen.  If you are removing tens of thousands of small files, then
> 100% CPU will be seen,
>
> IOWs, if there's enough work to be done, removing files will use all
> the available CPU. There's no problem with that.

Also, removing huge files which are completely in cache (recently
written, for example) will use considerable CPU time.

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