From: Norbert Preining <preining@logic.at>
To: Eric Sandeen <esandeen@redhat.com>
Cc: Ted Ts'o <tytso@mit.edu>, Eric Sandeen <sandeen@redhat.com>,
"linux-ext4@vger.kernel.org" <linux-ext4@vger.kernel.org>
Subject: Re: Ext4 slow on links
Date: Wed, 20 Jun 2012 14:18:44 +0900 [thread overview]
Message-ID: <20120620051844.GA7829@gamma.logic.tuwien.ac.at> (raw)
In-Reply-To: <BA050E9A-2385-4FF9-B41A-3A25F3FF066A@redhat.com>
Hi Eric,
On Di, 19 Jun 2012, Eric Sandeen wrote:
> blktrace of the actions would show you something interesting as well.
I tried to understand the output, but didn't get any information
that tells me something.
I rebooted into single user mode, started blktrace on sda, then run
time ls -l /..../dir/with/links/ >/dev/null, stopped the blktrace.
Then I run blkparse and btt etc to generate a variety of data.
Here are some output of the btt run:
==================== All Devices ====================
ALL MIN AVG MAX N
--------------- ------------- ------------- ------------- -----------
Q2Q 0.000002654 0.009716548 6.594440648 8953
Q2G 0.000001047 0.000001825 0.000011594 8913
G2I 0.000000908 0.000001561 0.000234317 8913
Q2M 0.000000908 0.000001046 0.000001536 41
I2D 0.000005378 0.001040528 1.572900300 8913
M2D 0.000014527 0.038626776 1.572908333 41
D2C 0.000098337 0.009050273 0.053790446 8954
Q2C 0.000108394 0.010266282 1.577191424 8954
==================== Device Overhead ====================
DEV | Q2G G2I Q2M I2D D2C
---------- | --------- --------- --------- --------- ---------
( 8, 0) | 0.0177% 0.0151% 0.0000% 10.0890% 88.1553%
---------- | --------- --------- --------- --------- ---------
Overall | 0.0177% 0.0151% 0.0000% 10.0890% 88.1553%
==================== Device Merge Information ====================
DEV | #Q #D Ratio | BLKmin BLKavg BLKmax Total
---------- | -------- -------- ------- | -------- -------- -------- --------
( 8, 0) | 8954 8913 1.0 | 8 9 1024 86872
==================== Device Q2Q Seek Information ====================
DEV | NSEEKS MEAN MEDIAN | MODE
---------- | --------------- --------------- --------------- | ---------------
( 8, 0) | 8954 193362127.3 0 | 0(538)
---------- | --------------- --------------- --------------- | ---------------
Overall | NSEEKS MEAN MEDIAN | MODE
Average | 8954 193362127.3 0 | 0(538)
==================== Device D2D Seek Information ====================
DEV | NSEEKS MEAN MEDIAN | MODE
---------- | --------------- --------------- --------------- | ---------------
( 8, 0) | 8913 194044831.4 0 | 0(497)
---------- | --------------- --------------- --------------- | ---------------
Overall | NSEEKS MEAN MEDIAN | MODE
Average | 8913 194044831.4 0 | 0(497)
==================== Plug Information ====================
DEV | # Plugs # Timer Us | % Time Q Plugged
---------- | ---------- ---------- | ----------------
( 8, 0) | 81( 0) | 0.002663579%
DEV | IOs/Unp IOs/Unp(to)
---------- | ---------- ----------
( 8, 0) | 1.2 0.0
---------- | ---------- ----------
Overall | IOs/Unp IOs/Unp(to)
Average | 1.2 0.0
==================== Active Requests At Q Information ====================
DEV | Avg Reqs @ Q
---------- | -------------
( 8, 0) | 0.1
.....
I don't know if that shows anything of interest, but if you need more,
and want to waste a bit of time looking at the data, I have uploaded
everything created into
http://www.logic.at/people/preining/BlkParse.tar.gz
size 5090853
md5sum 46db8455a04dcc4a602e34d21eecc6bd
In any case, thanks for your patience and support
Norbert
------------------------------------------------------------------------
Norbert Preining preining@{jaist.ac.jp, logic.at, debian.org}
JAIST, Japan TeX Live & Debian Developer
DSA: 0x09C5B094 fp: 14DF 2E6C 0307 BE6D AD76 A9C0 D2BF 4AA3 09C5 B094
------------------------------------------------------------------------
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next prev parent reply other threads:[~2012-06-20 5:18 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-20 0:20 Ext4 slow on links Norbert Preining
2012-06-20 2:19 ` Ted Ts'o
2012-06-20 3:38 ` Norbert Preining
2012-06-20 3:57 ` Eric Sandeen
2012-06-20 4:01 ` Norbert Preining
2012-06-20 5:18 ` Norbert Preining [this message]
2012-06-20 14:07 ` Eric Sandeen
2012-06-20 19:35 ` Eric Sandeen
2012-06-21 2:28 ` Norbert Preining
2012-06-21 4:05 ` Eric Sandeen
2012-06-21 4:50 ` Norbert Preining
2012-06-21 5:18 ` Andreas Dilger
2012-06-21 6:55 ` Norbert Preining
2012-06-22 9:53 ` Bernd Schubert
2012-06-22 14:08 ` Ted Ts'o
2012-06-20 3:15 ` Eric Sandeen
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