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High %user CPU in XFS

To: xfs@xxxxxxxxxxx
Subject: High %user CPU in XFS
From: Subranshu Patel <spatel.ml@xxxxxxxxx>
Date: Sun, 17 Feb 2013 21:20:46 +0530
Delivered-to: xfs@xxxxxxxxxxx
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 I created 2 filesystem on my system (RHEL 6.3, kernel 2.6.32) - XFS
and EXT4 and mounted them.

On both the filesystem I executed a program which performed the following:
- Create large number of directories
- Removing all the directories

During the execution of the program, I monitored the %user and %system
CPU usage (using sar command)

For EXT4 the %user was 1% and %system was 21%
For XFS the %user was 20% and %system was 52%

But I am not able to understand %user consumption, since %user reports
the CPU usage of the user level (application), shouldn't it be the
same for both EXT4 and XFS?

What are the factors that decide the %user component keeping in mind
that only the filesystem is different?

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