Re: sched: Avoid SMT siblings in select_idle_sibling() if possible

From: Mike Galbraith
Date: Tue Mar 27 2012 - 09:56:39 EST

On Mon, 2012-03-26 at 20:06 +0200, Peter Zijlstra wrote:

> The biggest regression came from tbench, wasn't that mostly a random
> number generator anyway?

That's dbench ;-) Tbench does wiggle around more than you'd like
though. I've never tracked, but in lots of running the thing, 2-3% you
can forget chasing, and I once bisected a 5% regression to an unrelated
change, reverted and re-applied the suspect a few times in disbelief,
and it tracked. You can't trust it _too_ much. I consider it a
reliable indicator that I'd better do more testing. If others agree,
it's a real regression, if not, it's those damn Elves 'n Gremlins ;-)


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