Messages in this thread | | | Date | Mon, 28 Jan 2013 12:21:45 +0100 | From | Ingo Molnar <> | Subject | Re: [patch] sched: minimalist select_idle_sibling() bouncing cow syndrome fix |
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* Mike Galbraith <bitbucket@online.de> wrote:
> On Mon, 2013-01-28 at 11:53 +0100, Ingo Molnar wrote: > > * Mike Galbraith <bitbucket@online.de> wrote: > > > > > If the previous CPU is cache affine and idle, select it. > > > > No objections in principle - but would be nice to have a > > changelog with numbers, % of improvement included and so? > > Well, that like was my changelog, guess it needs improvement. > > Take 2. > > sched: minimalist select_idle_sibling() bouncing cow syndrome fix > > If the previous CPU is cache affine and idle, select it. > > The current implementation simply traverses the sd_llc domain, > taking the first idle CPU encountered, which walks buddy pairs > hand in hand over the package, inflicting excruciating pain. > > 1 tbench pair (worst case) in a 10 core + SMT package: > > pre 15.22 MB/sec 1 procs > post 252.01 MB/sec 1 procs
Drool ... :-)
What would be a 'contrarian' test - i.e. a test where this could hurt most?
Thanks,
Ingo
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