Re: rq_affinity doesn't seem to work?

From: Matthew Wilcox
Date: Wed Jul 13 2011 - 13:10:20 EST


On Tue, Jul 12, 2011 at 10:30:35PM +0200, Jens Axboe wrote:
> It's probably the grouping, we need to do something about that. Does the
> below patch make it behave as you expect?

"something", absolutely. But there is benefit from doing some aggregation
(we tried disabling it entirely with the "well-known OLTP benchmark" and
performance went down).

Ideally we'd do something like "if the softirq is taking up more than 10%
of a core, split the grouping". Do we have enough stats to do that kind
of monitoring?

--
Matthew Wilcox Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours. We can't possibly take such
a retrograde step."
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