Low latency kernel for Quantal

Tim Gardner tim.gardner at canonical.com
Tue May 29 16:13:09 UTC 2012


At UDS I committed to adding a low latency flavour to Quantal if we
could collapse generic and virtual. It appears that we've been able to
do so.

After looking at the lowlatency kernel in Precise
(git://kernel.ubuntu.com/themuso/ubuntu-precise-lowlatency.git) it looks
like the required config changes are:

CONFIG_HZ=1000
CONFIG_NO_HZ=n
CONFIG_PREEMPT=y
CONFIG_PREEMPT_RCU=y

and some other config options that get enabled as a result of the above
changes.

The only relevant code patch is 'UBUNTU: SAUCE: Made kernel irq-threaded
by default' which changes the default behavior of forced IRQ threads to
enabled, and adds a kernel boot parameter to override the default. I
propose that we _not_ carry this patch in Quantal if the lowlatency
installer can add 'threadirqs' to the grub kernel command line.

Thoughts?

rtg
-- 
Tim Gardner tim.gardner at canonical.com



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