On Fri, Aug 26, 2011 at 08:20:57PM +0800, Wu Fengguang wrote: > On Fri, Aug 26, 2011 at 08:11:50PM +0800, Peter Zijlstra wrote: > > On Fri, 2011-08-26 at 19:26 +0800, Wu Fengguang wrote: > > > Now I get 3 figures. Test case is: run 1 dd write task for 300s, with > > > a "disturber" dd read task during roughly 120-130s. > > > > Ah, but ideally the disturber task should run in bursts of 100ms > > (<feedback period), otherwise your N is indeed mostly constant. > > Ah yeah, the disturber task should be a dd writer! Then we get > > - 120s: N=1 => N=2 > - 130s: N=2 => N=1 Here they are. The write disturber starts/stops around 150s. We got similar result as in the read disturber case, even though one disturbs N and the other impacts writeout bandwith. The original patchset is consistently performing much better :) Thanks, Fengguang
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