lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <1194873980.7179.31.camel@twins>
Date:	Mon, 12 Nov 2007 14:26:20 +0100
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	"Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>
Cc:	LKML <linux-kernel@...r.kernel.org>
Subject: Re: iozone write 50% regression in kernel 2.6.24-rc1

Single socket, dual core opteron, 2GB memory
Single SATA disk, ext3

x86_64 kernel and userland

(dirty_background_ratio, dirty_ratio) tunables

---- (5,10) - default

2.6.23.1-42.fc8 #1 SMP

          524288       4   59580   60356
          524288       4   59247   61101
          524288       4   61030   62831

2.6.24-rc2 #28 SMP PREEMPT

          524288       4   49277   56582
          524288       4   50728   61056
          524288       4   52027   59758
          524288       4   51520   62426


---- (20,40) - similar to your 8GB

2.6.23.1-42.fc8 #1 SMP

          524288       4  225977  447461
          524288       4  232595  496848
          524288       4  220608  478076
          524288       4  203080  445230

2.6.24-rc2 #28 SMP PREEMPT

          524288       4   54043   83585
          524288       4   69949  516253
          524288       4   72343  491416
          524288       4   71775  492653

---- (60,80) - overkill

2.6.23.1-42.fc8 #1 SMP

          524288       4  208450  491892
          524288       4  216262  481135
          524288       4  221892  543608
          524288       4  202209  574725
          524288       4  231730  452482

2.6.24-rc2 #28 SMP PREEMPT

          524288       4   49091   86471
          524288       4   65071  217566
          524288       4   72238  492172
          524288       4   71818  492433
          524288       4   71327  493954


While I see that the write speed as reported under .24 ~70MB/s is much
lower than the one reported under .23 ~200MB/s, I find it very hard to
believe my poor single SATA disk could actually do the 200MB/s for
longer than its cache 8/16 MB (not sure).

vmstat shows that actual IO is done, even though the whole 512MB could
fit in cache, hence my suspicion that the ~70MB/s is the most realistic
of the two.

I'll have to look into what iozone actually does though and why this
patch makes the output different.

FWIW - because its a single backing dev it does get to 100% of the dirty
limit after a few runs, so not sure what makes the difference.

Download attachment "signature.asc" of type "application/pgp-signature" (190 bytes)

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ