Re: General question (scheduler) with SSDs?

On Fri, Feb 20, 2009 at 10:43, Sitsofe Wheeler [off-list ref] wrote:

Whoops, I didn't mean to send that previous half formed mail :) Sorry.

On Thu, Feb 19, 2009 at 08:38:38AM -0500, Justin Piszcz wrote:

quoted

I was curious if anyone had done any benchmarks and/or has conclusive
information, what is the best Linux scheduler to use with SSDs?

Noop?
CFQ?
AS?
Deadline?

As mentioned in another mail there was a discussion on
http://lkml.org/lkml/2009/1/31/28 and long thread talking about the
introduction of the rotational flag here
http://lkml.org/lkml/2009/1/5/340 . Cheapo SSDs or even USB keys are not
auto detected as non-rotational devices by the kernel and after a bit of
poking about I've come up with the following udev rules for my
particular cases:

SUBSYSTEM=="block", TEST=="/sys$devpath/queue/rotational", ATTRS{model}=="ASUS-PHISON *", RUN+="/bin/sh -c 'echo 0 > /sys$devpath/queue/rotational'"

Udev can write to the attribute itself. This should be all you need:
  SUSBSYTEM=="block", ATTRS{model}=="ASUS-PHISON *", ATTR{queue/rotational}="1"

Kay