From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755287Ab1KQB7T (ORCPT ); Wed, 16 Nov 2011 20:59:19 -0500 Received: from mailout-de.gmx.net ([213.165.64.22]:53668 "HELO mailout-de.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754749Ab1KQB7S (ORCPT ); Wed, 16 Nov 2011 20:59:18 -0500 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX1+0dI8845u0kC4A3TMUVRt9OZNG0D4iadzu4/ukKu Bq0iNSt/skKxd0 Subject: Re: sched: Avoid SMT siblings in select_idle_sibling() if possible From: Mike Galbraith To: Suresh Siddha Cc: Peter Zijlstra , linux-kernel , Ingo Molnar , Paul Turner In-Reply-To: <1321468646.11680.2.camel@sbsiddha-desk.sc.intel.com> References: <1321350377.1421.55.camel@twins> <1321406062.16760.60.camel@sbsiddha-desk.sc.intel.com> <1321435455.5072.64.camel@marge.simson.net> <1321468646.11680.2.camel@sbsiddha-desk.sc.intel.com> Content-Type: text/plain; charset="UTF-8" Date: Thu, 17 Nov 2011 02:59:13 +0100 Message-ID: <1321495153.5100.7.camel@marge.simson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.32.1 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2011-11-16 at 10:37 -0800, Suresh Siddha wrote: > On Wed, 2011-11-16 at 01:24 -0800, Mike Galbraith wrote: > > At SIBLING, group = 0,4 = 0x5, 0x5 & 0xff = 1 = target. > > Mike, At the sibling level, domain span will be 0,4 which is 0x5. But > there are two individual groups. First group just contains cpu0 and the > second group contains cpu4. > > So if cpu0 is busy, we will check the next group to see if it is idle > (which is cpu4 in your example). So we will return cpu-4. Oh duh, right. > It should be ok. Isn't it? Nope, wasn't ok. I'll double check today though, and bend, spindle and/or mutilate as required. -Mike