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From: bugzilla-daemon@bugzilla.kernel.org
To: linux-ext4@vger.kernel.org
Subject: [Bug 71641] Unreasonable performance degradation in ext4 with full data journaling
Date: Wed, 19 Mar 2014 09:35:03 +0000	[thread overview]
Message-ID: <bug-71641-13602-EJokyeogGw@https.bugzilla.kernel.org/> (raw)
In-Reply-To: <bug-71641-13602@https.bugzilla.kernel.org/>

https://bugzilla.kernel.org/show_bug.cgi?id=71641

--- Comment #3 from Chia-Hung Chang <fredchang.tc@gmail.com> ---
Test command :  dd if=/dev/zero of=/share/CACHEDEV2_DATA/orderno5G bs=1M
count=5120

The results of block trace can be download as follow.
https://dl.dropboxusercontent.com/u/32959539/blktrace_original_data.7z

The results of btt can be download as follow.
https://dl.dropboxusercontent.com/u/32959539/blktrace_output.7z

There are three folders:
/journal              -->ext4,data=journal              with 375MB/s
/order_delalloc       -->ext4,data=ordered,delalloc     with 937MB/s
/order_nodelalloc     -->ext4,data=ordered,nodelalloc   with 353MB/s


The size of write request with data=ordered,delalloc is 64k mostly.
The size of write requests with data=journal and data=ordered,nodelalloc are 4k
mostly. 

If we observe the average Q2Q in btt results, which means time interval between
requests, we have

/journal           0.00081
/order_nodelalloc  0.00031

It seems to be the reason of performance degradation.
Is any one know why the time interval of requests is significantly longer with
data=journal?

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  parent reply	other threads:[~2014-03-19 18:28 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-03-07 11:39 [Bug 71641] New: Unreasonable performance degradation in ext4 with full data journaling bugzilla-daemon
2014-03-07 16:20 ` Theodore Ts'o
2014-03-07 16:20 ` [Bug 71641] " bugzilla-daemon
2014-03-07 17:57 ` bugzilla-daemon
2014-03-19  9:35 ` bugzilla-daemon [this message]
2014-03-20  4:09 ` bugzilla-daemon
2014-03-20 12:47 ` bugzilla-daemon
2014-03-21  8:16 ` bugzilla-daemon
2014-03-21  8:17 ` bugzilla-daemon
2014-03-21  8:44 ` bugzilla-daemon
2014-03-21  8:48 ` bugzilla-daemon
2014-03-21 16:04 ` bugzilla-daemon
2014-03-26 10:30 ` bugzilla-daemon
2014-03-26 13:40 ` bugzilla-daemon
2014-03-28 10:23 ` bugzilla-daemon
2014-03-28 10:55 ` bugzilla-daemon

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