Fix:<br />
<a href="http:<a href="mailto://www.archivum.info/linux-ide@vger.kernel.org">//www.archivum.info/linux-ide@vger.kernel.org</a>/2010-02/00243/bad-performance-with-SSD-since-kernel-version-2.6.32.html">http:<a href="mailto://www.archivum.info/linux-ide@vger.kernel.org">//www.archivum.info/linux-ide@vger.kernel.org</a>/2010-02/00243/bad-performance-with-SSD-since-kernel-version-2.6.32.html</a> [<a href="http:<a href="mailto://www.archivum.info/linux-ide@vger.kernel.org">//www.archivum.info/linux-ide@vger.kernel.org</a>/2010-02/00243/bad-performance-with-SSD-since-kernel-version-2.6.32.html" target="_blank">^</a>]<br />
<br />
Copied from:<br />
<a href="http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=642729">http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=642729</a> [<a href="http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=642729" target="_blank">^</a>]<br />
<br />
After adding a ssd (OCZ Vertex Plus 60GB) to my squeeze system (debian kernel 2.6.32) <br />
I was disappointed about its performance, as it was advertised with 185 MB/s.<br />
<br />
/dev/sdb:<br />
Timing buffered disk reads: 214 MB in 3.01 seconds = 71.04 MB/sec<br />
<br />
However, when running recent knoppix (kernel 3.0.4) I got the expected performance:<br />
<br />
/dev/sdb:<br />
Timing buffered disk reads: 490 MB in 3.00 seconds = 163.07 MB/sec<br />
<br />
After googling, I found that this has been reported before:<br />
<br />
<a href="http:<a href="mailto://www.archivum.info/linux-ide@vger.kernel.org">//www.archivum.info/linux-ide@vger.kernel.org</a>/2010-02/00243/bad-performance-with-SSD-since-kernel-version-2.6.32.html">http:<a href="mailto://www.archivum.info/linux-ide@vger.kernel.org">//www.archivum.info/linux-ide@vger.kernel.org</a>/2010-02/00243/bad-performance-with-SSD-since-kernel-version-2.6.32.html</a> [<a href="http:<a href="mailto://www.archivum.info/linux-ide@vger.kernel.org">//www.archivum.info/linux-ide@vger.kernel.org</a>/2010-02/00243/bad-performance-with-SSD-since-kernel-version-2.6.32.html" target="_blank">^</a>]<br />
<br />
It seems that early versions of kernel 2.6.32 have a bug that results in bad performance of some<br />
ssds (maybe all, at least the 'OCZ Vertex Plus 60GB' and the 'Super Talent Ultradrive GX MLC 64GB').<br />
Reverting the patch as described in the discussion solved the problem for me. I now have the <br />
desired performance.<br />
<br />
Thus, I would suggest to revert the patch "block: improve queue_should_plug() by looking at <br />
IO depths" in kernel 2.6.32 for squeeze in order to get full ssd performance. I think the bugfix <br />
is important as an increasing number of users havs ssds and the bug more or less breaks ssd <br />
performance in squeeze.<br />
<br />
Juergen<br />
<br />
<br />
<br />
-- System Information:<br />
Debian Release: 6.0.2<br />
APT prefers stable-updates<br />
APT policy: (500, 'stable-updates'), (500, 'stable')<br />
Architecture: i386 (i686)<br />
<br />
Kernel: Linux 2.6.32-5-686 (SMP w/2 CPU cores)<br />
Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8)<br />
Shell: /bin/sh linked to /bin/dash<br />
<br />
Versions of packages linux-image-2.6.32-5-686 depends on:<br />
ii coreutils 8.5-1 GNU core utilities<br />
ii debconf [debconf-2.0] 1.5.36.1 Debian configuration management sy<br />
<br />
linux-image-2.6.32-5-686 recommends no packages.<br />
<br />
Versions of packages linux-image-2.6.32-5-686 suggests:<br />
pn fdutils <none> (no description available)<br />
pn ksymoops <none> (no description available)<br />
pn linux-doc-2.6.32-5-686 | linu <none> (no description available)<br />
pn linux-image-2.6.32-5-686-dbg <none> (no description available)<br />
<br />
-- debconf information:<br />
linux-image-2.6.32-5-686/preinst/failed-to-move-modules-2.6.32-5-686:<br />
linux-image-2.6.32-5-686/postinst/kimage-is-a-directory:<br />
linux-image-2.6.32-5-686/postinst/depmod-error-initrd-2.6.32-5-686: false<br />
linux-image-2.6.32-5-686/postinst/ignoring-do-bootloader-2.6.32-5-686:<br />
linux-image-2.6.32-5-686/postinst/old-system-map-link-2.6.32-5-686: true<br />
linux-image-2.6.32-5-686/postinst/missing-firmware-2.6.32-5-686:<br />
* linux-image-2.6.32-5-686/preinst/overwriting-modules-2.6.32-5-686: false<br />
linux-image-2.6.32-5-686/prerm/removing-running-kernel-2.6.32-5-686: true<br />
linux-image-2.6.32-5-686/postinst/depmod-error-2.6.32-5-686: false<br />
linux-image-2.6.32-5-686/postinst/old-dir-initrd-link-2.6.32-5-686: true<br />
linux-image-2.6.32-5-686/preinst/abort-overwrite-2.6.32-5-686:<br />
* linux-image-2.6.32-5-686/preinst/already-running-this-2.6.32-5-686:
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