xfs
[Top] [All Lists]

HUGE XFS regression in 2.6.32 upto 2.6.38

To: xfs-oss <xfs@xxxxxxxxxxx>
Subject: HUGE XFS regression in 2.6.32 upto 2.6.38
From: Raz <raziebe@xxxxxxxxx>
Date: Tue, 12 Apr 2011 10:58:53 +0300
Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:from:date:message-id:subject:to :content-type:content-transfer-encoding; bh=g6mHvcquVfapgDO+0WlosQ2fOIzUPS6WejI6AB/DxB0=; b=TAuVHjqfdcmevcbTW0DRxzVJhY5XXu45oEltjSGSQtjPB4j9HfBzJLu/LoyIpyrLb3 zO+IRAZrnH2gI9kcyUcc2CXUA61pk/FItjZnKi6fC/I7SIoGJzWfM6rhMbqi/goUqmOo QroyECtowz0VjetnIa/LOAHFCia172C0YxqLg=
Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:from:date:message-id:subject:to:content-type :content-transfer-encoding; b=okpTEuH4+ieM3tlH5sdgpBowNK40gJD1wfNF1fU1zmO2Zi47fn1r2UhDbnVhzF4M8J LtixuMZhMcmYWzbzOWSqY0Mb/dILt+TFjgO2b269CyUCtYfy07ozKRO//JhH1GPVfRtm XamHkOX9Y+3AcJg7+sdbmnIH+PVqDJ2ZaqF+s=
Christoph Hello
I am testing 2.6.38 with AIM benchmark.
I compared 2.6.38 to 2.6.27 and I noticed that 2.6.27 is much better
than 2.6.38 when
doing sync random writes test over an xfs regular file over native
Linux partition on top common sata disk.
I git bisected the problem and I reached this SHA1:
commit 13e6d5cdde0e785aa943810f08b801cadd0935df
Author: Christoph Hellwig <hch@xxxxxx>
Date:   Mon Aug 31 21:00:31 2009 -0300

   xfs: merge fsync and O_SYNC handling

   The guarantees for O_SYNC are exactly the same as the ones we need to
   make for an fsync call (and given that Linux O_SYNC is O_DSYNC the
   equivalent is fdadatasync, but we treat both the same in XFS), except
   with a range data writeout.  Jan Kara has started unifying these two
   path for filesystems using the generic helpers, and I've started to
   look at XFS.
...


The bellow two tests presents the how different performance is before and patch:
#test 16) bisect 11
------------------------------------------------------------------------------------------------------------
 Test        Test        Elapsed  Iteration    Iteration          Operation
Number       Name      Time (sec)   Count   Rate (loops/sec)    Rate (ops/sec)
------------------------------------------------------------------------------------------------------------
    1 sync_disk_rw        30.71         19    0.61869         1583.85
Sync Random Disk Writes (K)/second
------------------------------------------------------------------------------------------------------------

#test 17 ) bisect 12
------------------------------------------------------------------------------------------------------------
    1 sync_disk_rw        69.05          1    0.01448           37.07
Sync Random Disk Writes (K)/second
------------------------------------------------------------------------------------------------------------


Regards
Raz Ben-Yehuda


 Reply
 Reply to all
 Forward

<Prev in Thread] Current Thread [Next in Thread>