Karmic I/O scheduler issues

John Mahoney jmahoney at waav.com
Tue Sep 29 21:57:22 UTC 2009

On Tue, Sep 29, 2009 at 4:37 PM, Tim Gardner <tim.gardner at canonical.com>wrote:

> I've been messing with I/O scheduler settings in the last couple of
> uploads. We found that CFQ has some serious issues that contributed to
> delayed boot times, so I changed the default to Deadline in
> 2.6.31-10.35. Scott Remnant reported that changing to Deadline shaved 40
> seconds off his boot.
> Since then I found this info: http://bugs.launchpad.net/bugs/436342
> I've been running a kernel with this patch and CFQ enabled. Perhaps some
> other folks could compare and contrast Deadline v.s. CFQ using their
> workloads. I find that CFQ is working a bit better then Deadline. I can
> run a 'make -j8' kernel build and still watch video while also playing
> music and reading email (without _too_ much stalling). Deadline is
> noticeably less smooth when the load average approaches 8.
> Adventurous types can try this kernel from
> http://kernel.ubuntu.com/~rtg/2.6.31-11-NEW_FAIR_SLEEPERS<http://kernel.ubuntu.com/%7Ertg/2.6.31-11-NEW_FAIR_SLEEPERS>
> (when its done copying)

It would be nice if Ubuntu had debugfs enabled by default so users could
more easily adjust these settings.

Such as discussed here: http://lkml.org/lkml/2008/5/2/67

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