Messages in this thread | | | Date | Thu, 24 Apr 2014 18:52:19 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 3/3] sched, fair: Stop searching for tasks in newidle balance if there are runnable tasks |
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On Thu, Apr 24, 2014 at 09:43:09AM -0700, Jason Low wrote: > If the below patch is what you were referring to, I believe this > can help too. This was also something that I was testing out before > we went with those patches which compares avg_idle with idle balance > cost. I recall seeing somewhere around a +7% performance improvement > in at least least 1 of the AIM7 workloads. I can do some more testing > with this.
Yes, exactly that.
I can't remember the details, but I suspect we feared the less agressive idle balance due to that patch (it will only pull a single task, instead of multiple) would cause more idle_balance invocations and thereby decrease throughput.
So I suppose something with _many_ bursty threads which leads to severe inequalities would be the workload to trigger that.
Not sure we've ever seen that.. maybe Mike remembers, he seems to have a head for such details.
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