Messages in this thread | | | Date | Thu, 30 Oct 2014 15:46:34 +0100 | From | Peter Zijlstra <> | Subject | Re: [RFD PATCH 10/10] sched: io_latency: Tracking via buckets |
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On Wed, Oct 22, 2014 at 03:57:53PM +0200, Daniel Lezcano wrote: > The size of the bucket is the bucket interval and represent the resolution > of the statistic model. Eg with a bucket interval of 1us, it leads us to > do statitics on all numbers, with of course a bad prediction because the > number of latencies is big. A big interval can give better statistics, > but can give us a misprediction as the interval is larger. > > Choosing the size of the bucket interval vs the idle sleep time is the > tradeoff to find. With a 200us bucket interval, the measurements show > we still have good predictions, less mispredictions and cover the idle > state target residency. >
For the record:
The suggestion in DUS was to align the bucket sizes with the various break even times of the actual C states.
I forgot who suggested this; it might have been Morten; but it seems to make sense.
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