On Sun, 21 Feb 2010 16:00:35 -0600
Robert Hancock <hancockrwd@xxxxxxxxx> wrote:
> Hmm.. Well, that's not it then.. I suspect a bisection is likely the
> easiest route at this point..
fb1e75389bd06fd5987e9cda1b4e0305c782f854 is the first bad commit
commit fb1e75389bd06fd5987e9cda1b4e0305c782f854
Author: Jens Axboe <jens.axboe@xxxxxxxxxx>
Date: Thu Jul 30 08:18:24 2009 +0200
block: improve queue_should_plug() by looking at IO depths
Instead of just checking whether this device uses block layer
tagging, we can improve the detection by looking at the maximum
queue depth it has reached. If that crosses 4, then deem it a
queuing device.
This is important on high IOPS devices, since plugging hurts
the performance there (it can be as much as 10-15% of the sys
time).
Signed-off-by: Jens Axboe <jens.axboe@xxxxxxxxxx>
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=fb1e75389bd06fd5987e9cda1b4e0305c782f854
Without that patch my SSD (Super Talent Ultradrive GX MLC 64GB)
reaches about 200MB/s sequentiell read. After applying the patch it
reaches only 70MB/s.
Note: Added Jens to CC.
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