Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030504AbWBNIJ4 (ORCPT ); Tue, 14 Feb 2006 03:09:56 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030493AbWBNIJ4 (ORCPT ); Tue, 14 Feb 2006 03:09:56 -0500 Received: from mtagate3.de.ibm.com ([195.212.29.152]:16090 "EHLO mtagate3.de.ibm.com") by vger.kernel.org with ESMTP id S1030504AbWBNIJz (ORCPT ); Tue, 14 Feb 2006 03:09:55 -0500 Date: Tue, 14 Feb 2006 09:09:42 +0100 From: Heiko Carstens To: Olaf Hering Cc: Ingo Molnar , Hannes Reinecke , linux-kernel@vger.kernel.org, Andrew Morton Subject: Re: calibrate_migration_costs takes ages on s390 Message-ID: <20060214080942.GC19896@osiris.boeblingen.de.ibm.com> References: <20060213102634.GA4677@osiris.boeblingen.de.ibm.com> <20060213104645.GA17173@elte.hu> <20060213234254.GA5368@suse.de> <20060214000807.GA6188@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060214000807.GA6188@suse.de> User-Agent: mutt-ng/devel-r781 (Linux) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2036 Lines: 45 > > We did a bit of testing, -rc2-git3 + the patch below was still ok. > > > > [PATCH] s390: earlier initialization of cpu_possible_map > > 9733e2407ad2237867cb13c04e7d619397fa3090 > > I need to double check, but -git5 + that patch was reported to be slow. I did a quick git bisect search. This is one is the hurting one: Author: Ingo Molnar 2006-02-07 21:58:54 Committer: Linus Torvalds 2006-02-08 01:12:33 Parent: 8519fb30e438f8088b71a94a7d5a660a814d3872 ([PATCH] mm: compound release fix) Child: 0d4c3e7a8c65892c7d6a748fdbb4499e988880db ([PATCH] unshare system call -v5: Documentation file) [PATCH] Fix spinlock debugging delays to not time out too early The spinlock-debug wait-loop was using loops_per_jiffy to detect too long spinlock waits - but on fast CPUs this led to a way too fast timeout and false messages. The fix is to include a __delay(1) call in the loop, to correctly approximate the intended delay timeout of 1 second. The code assumes that every architecture implements __delay(1) to last around 1/(loops_per_jiffy*HZ) seconds. Signed-off-by: Ingo Molnar Cc: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds I guess we're once again suffering from being a virtualized platform: the formerly used call to cpu_relax() informed the underlying hypervisor that we want to give up the current cpu while __delay() keeps it. Unless we're scheduled away involuntarily. The "Detect Soft Lockups" option doesn't make too much sense too on our platform, since we get a lot of false positives. Quick fix: turn off the options CONFIG_DEBUG_SPINLOCK and CONFIG_DETECT_SOFTLOCKUP. Heiko - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/