Re: [patch] Re: PostgreSQL pgbench performance regression in 2.6.23+

Mike Galbraith
2008-06-07T14:16:35Z

On Sat, 2008-06-07 at 15:07 +0200, Peter Zijlstra wrote:
> On Sat, 2008-06-07 at 14:50 +0200, Mike Galbraith wrote:
> > Since I tested mysql+oltp and made the dang pdf of the results, I may
> > as well actually attach the thing <does that before continuing...>.
> >
> > BTW, I have a question wrt avg_overlap. When a wakeup cause the current
> > task to begin sharing CPU with a freshly awakened task, the current task
> > is tagged.. but the wakee isn't. How come? If one is sharing, so is
> > the other.
>
> avg_overlap is about measuring how long we'll run after waking someone
> else. The other measure, how long our waker shares the cpu with us,
> hasn't proven to be relevant so far.

Yeah wrt relevance, I've been playing with making it mean this and that,
with approx 0 success ;-) If it's a measure of how long we run after
waking though, don't we need to make sure it's not a cross CPU wakeup?

-Mike