From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751492AbcGMWFe (ORCPT ); Wed, 13 Jul 2016 18:05:34 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:41531 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751272AbcGMWF0 (ORCPT ); Wed, 13 Jul 2016 18:05:26 -0400 Date: Wed, 13 Jul 2016 15:05:25 -0700 From: Andrew Morton To: Manfred Spraul Cc: "H. Peter Anvin" , Peter Zijlstra , Davidlohr Bueso , LKML , Thomas Gleixner , Ingo Molnar , 1vier1@web.de, felixh@informatik.uni-bremen.de Subject: Re: [PATCH 0/2] ipc/sem.c: sem_lock fixes Message-Id: <20160713150525.8f703dfa5e83a534f8a51106@linux-foundation.org> In-Reply-To: <1468386412-3608-1-git-send-email-manfred@colorfullife.com> References: <1468386412-3608-1-git-send-email-manfred@colorfullife.com> X-Mailer: Sylpheed 3.4.1 (GTK+ 2.24.23; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 13 Jul 2016 07:06:50 +0200 Manfred Spraul wrote: > Hi Andrew, Hi Peter, > > next version of the sem_lock() fixes: > The patches are again vs. tip. > > Patch 1 is ready for merging, Patch 2 is for review. > > - Patch 1 is the patch as in -next since January > It fixes the race that was found by Felix. > - Patch 2 removes the memory barriers that are part of the qspinlock > code. > - (The hysteresis patch would be patch 3. The risk of regressions > can't be ruled out, thus it must wait for benchmarks from real > workload tests) I think you're saying that if these two patches cause performance regressions, we will need ipc-sem-sem_lock-with-hysteresis.patch? Is that even necessary? If your testing shows that ipc-sem-sem_lock-with-hysteresis.patch makes things faster then in it goes, surely?