Re: allow the load to grow upto its cpu_power (was Re: [Patch] don't kick ALB in the presence of pinned task)

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Siddha, Suresh B wrote:
On Thu, Aug 11, 2005 at 01:09:10PM +1000, Nick Piggin wrote:

I have a variation on the 2nd part of your patch which I think
I would prefer. IMO it kind of generalises the current imbalance
calculation to handle this case rather than introducing a new
special case.


There is a difference between our changes. When the system is lightly loaded, my patch minimizes the number of groups picking up that load. This will help in power savings for example in the context of CMP. There are more changes required (user or kernel) for complete power savings, but this is a direction towards that.

How about this patch?

Well, it is a departure from our current idea of balancing.
I would prefer to use my patch initially to fix the _bug_
you found, then we can think about changing policy for
power savings.

Main things I'm worried about:

Idle time regressions that pop up any time we put
restrictions on balancing.

This can tend to unbalance memory controllers (eg. on POWER5,
CMP Opteron) which can be a performance problem on those
systems.

Lastly, complexity in the calculation.

--
SUSE Labs, Novell Inc.

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