From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755932Ab0C3Sez (ORCPT ); Tue, 30 Mar 2010 14:34:55 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:34139 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755538Ab0C3Sey (ORCPT ); Tue, 30 Mar 2010 14:34:54 -0400 Subject: Re: [PATCH] increase PREEMPT_BITS to 12 to avoid overflow when starting KVM From: Peter Zijlstra To: Rik van Riel Cc: linux-kernel@vger.kernel.org, avi@redhat.com, aarcange@redhat.com, akpm@linux-foundation.org, Kent Overstreet , Ingo Molnar , tglx In-Reply-To: <4BB23D64.70502@redhat.com> References: <20100330133634.2f1bf3d6@cuia.bos.redhat.com> <1269971802.5258.524.camel@laptop> <4BB23D64.70502@redhat.com> Content-Type: text/plain; charset="UTF-8" Date: Tue, 30 Mar 2010 20:34:49 +0200 Message-ID: <1269974089.5258.565.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2010-03-30 at 14:05 -0400, Rik van Riel wrote: > > Also, you'll need to convince mingo and tglx too.. taking that many > > spinlocks is utter suckage.. > > No argument there. I can't think of an alternative to mm_take_all_locks > though. Andrea? Well there's altneratives enough, back when this got introduces quite a few got mentioned too, but they all make the !mm_take_all_locks() lock side slower so Andrea didn't like them. I think one of them got mentioned in yesterday's thread as well. Another alternative is making all those spinlocks mutexes, that will get rid of that massive !preempt section too.