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Date: Tue, 25 Sep 2012 04:49:26 +0200 From: Mike Galbraith <efault@....de> To: Linus Torvalds <torvalds@...ux-foundation.org> Cc: Borislav Petkov <bp@...en8.de>, Peter Zijlstra <a.p.zijlstra@...llo.nl>, Mel Gorman <mgorman@...e.de>, Nikolay Ulyanitsky <lystor@...il.com>, linux-kernel@...r.kernel.org, Andreas Herrmann <andreas.herrmann3@....com>, Andrew Morton <akpm@...ux-foundation.org>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...nel.org>, Suresh Siddha <suresh.b.siddha@...el.com> Subject: Re: 20% performance drop on PostgreSQL 9.2 from kernel 3.5.3 to 3.6-rc5 on AMD chipsets - bisected On Mon, 2012-09-24 at 19:11 -0700, Linus Torvalds wrote: > In the not-so-distant past, we had the intel "Dunnington" Xeon, which > was iirc basically three Core 2 duo's bolted together (ie three > clusters of two cores sharing L2, and a fully shared L3). So that was > a true multi-core with fairly big shared L2, and it really would be > sad to not use the second core aggressively. Ah. That's what I did to select_idle_sibling() in a nutshell, converted the problematic large L3 packages into multiple ~core2duo pairs, modulo shared L2 'course. Bounce proof, and on Westmere, the jabbering back and forth in L3 somehow doesn't hurt as much as expected, so the things act (more or less, L2 traffic _does_ matter;) like the real deal. -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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