Messages in this thread | | | Date | Tue, 22 Oct 2013 05:35:12 -0400 | From | Johannes Weiner <> | Subject | Re: [patch 0/8] mm: thrash detection-based file cache sizing v5 |
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On Mon, Oct 21, 2013 at 11:26:43AM +0200, Vlastimil Babka wrote: > On 10/10/2013 11:46 PM, Johannes Weiner wrote: > > Hi everyone, > > > > here is an update to the cache sizing patches for 3.13. > > > > Changes in this revision > > > > o Drop frequency synchronization between refaulted and demoted pages > > and just straight up activate refaulting pages whose access > > frequency indicates they could stay in memory. This was suggested > > by Rik van Riel a looong time ago but misinterpretation of test > > results during early stages of development took me a while to > > overcome. It's still the same overall concept, but a little simpler > > and with even faster cache adaptation. Yay! > > Oh, I liked the previous approach with direct competition between the > refaulted and demoted page :) Doesn't the new approach favor the > refaulted page too much? No wonder it leads to faster cache adaptation, > but could it also cause degradations for workloads that don't benefit > from it? Were there any tests for performance regressions on workloads > that were not the target of the patchset?
If anything, it's unfair to refaulting pages because it requires 3 references before they are activated instead of the regular 2.
We don't do the direct competition for regular in-core activation, either, which has the same theoretical problem but was never an issue in the real world. Not that I know of anyway.
I ran a standard battery of mmtests (kernbench, dbench, postmark, micro, fsmark, what have you) and did not notice any regressions.
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