> > On Tue, Sep 17, 2013 at 11:44:22AM -0400, Doug Hughes wrote: > >> Oh, and P95/P99 distributions (commonly used for billing by network > >> carriers on MPLS) > > > > If you're only paying attention to p95/p99 in relation to network you're > > likely to be missing interesting and useful information. > > e.g. knowing that on average a user gets a page returned in 2 seconds is > > great, but if your p95 is out in the 30 second region that's a number of > > potentially unhappy users. > > I'd see the ideal goal as getting your mean as low as possible *and* your > > p95/p99 as close to your mean as possible :) > > From my experience p95/p99 data is about consumption not latency/performance > metrics. > > There are a number people who look at web performance metrics with percentile > latency metrics. Amazon is the most known big company that does this, but I > know that Google definitely does this as well. Amazon talks about it as > TP50, TP90, TP99, so on. TP for transaction percentile.
Oh, I'm not saying people *don't* do what you're describing (and it has all of the outlier problems Doug mentions), but the most common usage, by far, for p95/p99 metrics, is in billing for internet consumption/peering. D
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