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Date: Sat, 26 May 2012 08:37:39 +0200 From: Mike Galbraith <efault@....de> To: Peter Zijlstra <peterz@...radead.org> Cc: lkml <linux-kernel@...r.kernel.org>, Suresh Siddha <suresh.b.siddha@...el.com>, Paul Turner <pjt@...gle.com>, Arjan Van De Ven <arjan@...ux.intel.com> Subject: Re: [rfc][patch] select_idle_sibling() inducing bouncing on westmere On Fri, 2012-05-25 at 08:14 +0200, Mike Galbraith wrote: > On Thu, 2012-05-24 at 15:20 +0200, Peter Zijlstra wrote: > > On Thu, 2012-05-24 at 15:17 +0200, Peter Zijlstra wrote: > > > For power7 with 4 smt it would end up as 1230 I guess. > > > > One more thing, in light of that, can't you simplify the core stuff to > > be a simple shift as well? map them 123450, does it really matter to > > pair them off like 103254 ? > > In my head it does. Buddies need to be glued together so we can use > them as a team to convert overlap and kick butt on ramp up. Ew. 3.4 went broke for Q6600, and performance went... far far away. [ 0.200057] CPU0 attaching sched-domain: [ 0.204016] domain 0: span 0-3 level MC [ 0.208015] groups: 0 1 2 3 [ 0.210970] CPU1 attaching sched-domain: [ 0.212014] domain 0: span 0-3 level MC [ 0.216016] groups: 1 2 3 0 [ 0.220016] CPU2 attaching sched-domain: [ 0.224015] domain 0: span 0-3 level MC [ 0.228016] groups: 2 3 0 1 [ 0.232015] CPU3 attaching sched-domain: [ 0.236016] domain 0: span 0-3 level MC [ 0.240017] groups: 3 0 1 2 11.791806 usecs/loop -- avg 11.534552 173.4 KHz Cause: sometimes during boot, hw Siamese twins are 0-1 2-3, and sometimes, as in this boot, 0-3 1-2, so busted groups above does the worst thing possible. When twins are 0-1 2-3, busted groups doesn't matter with $subject patch applied, it glues Siamese twins back together. During this boot, it created Siamese aliens from hell. -Mike -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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