Start irqbalance by default

[Robbie Williamson]

My main concern is the affect on boot performance.  I'd like to see
bootchart data showing it doesn't slow down our boot on our reference
hardware (Dell Mini 10v SSD and HDD).  If we can be confident that
performance is not negatively affected, then I'm personally fine with
starting it by default.

-Robbie

On Fri, 2010-01-15 at 14:38 +0100, Soren Hansen wrote: 
> On Mon, Jan 11, 2010 at 11:23:43AM +0000, Matt Zimmerman wrote:
> > I'm not sure why it needs to run all the time, though, rather than
> > (say) as a cron job.  It has a --oneshot option which might be
> > suitable for this.
> 
> FWIW, it automatically switches to oneshot mode on single-CPU,
> multi-core systems, so it only sticks around on "actual" multi-CPU
> systems. I think those are a rare breed among desktop systems.
> 
> >> Does userspace have more information about which processes are
> >> running and what they are going to do? If so, doesn't that involve
> >> more IPC and thus wakeups? If not, why isn't that alternative
> >> strategy implemented in the kernel itself (right now it seems that
> >> the scheduling would be done at two places?)
> > It's looking at statistical behavior, e.g. how many IRQs particular
> > devices have generated over a period of minutes or hours, and uses
> > that information to provide the kernel with scheduling hints.  I think
> > running it a few times per hour at most would be sufficient.
> 
> I don't think a rescheduling interval of more than a minute is really
> very useful.
> 
> >> Chuck, did you actually intend to install this on all desktop systems
> >> as well, or just servers (where performance might matter more).
> > It seems appropriate for both.
> 
> I concur.
> 


-- 
Robbie Williamson                                     robbie at ubuntu.com
Ubuntu                                         robbiew[irc.freenode.net]                               

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