Messages in this thread | | | From | "Chen, Kenneth W" <> | Subject | RE: Default cache_hot_time value back to 10ms | Date | Tue, 5 Oct 2004 22:52:26 -0700 |
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Andrew Morton wrote on Tuesday, October 05, 2004 9:51 PM > > > It sounds like this needs to be runtime tunable? > > > > > > > I'd say it is probably too low level to be a useful tunable (although > > for testing I guess so... but then you could have *lots* of parameters > > tunable). > > This tunable caused an 11% performance difference in (I assume) TPCx. > That's a big deal, and people will want to diddle it. > > If one number works optimally for all machines and workloads then fine. > > But yes, avoiding a tunable would be nice, but we need a tunable to work > out whether we can avoid making it tunable ;)
Just to throw in some more benchmark numbers, we measured that specjbb throughput went up by about 0.3% with cache_hot_time set to 10ms compare to default 2.5ms. No measurable speedup/regression on volanmark (we just tried 10 and 2.5ms).
- Ken
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