From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750763AbWJPNsM (ORCPT ); Mon, 16 Oct 2006 09:48:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750769AbWJPNsM (ORCPT ); Mon, 16 Oct 2006 09:48:12 -0400 Received: from cantor2.suse.de ([195.135.220.15]:18144 "EHLO mx2.suse.de") by vger.kernel.org with ESMTP id S1750763AbWJPNsL (ORCPT ); Mon, 16 Oct 2006 09:48:11 -0400 To: Andrew Morton Cc: lkml , johnstul@us.ibm.com Subject: Re: [PATCH] i386 Time: Avoid PIT SMP lockups References: <1160596462.5973.12.camel@localhost.localdomain> <20061011142646.eb41fac3.akpm@osdl.org> <1160606911.5973.36.camel@localhost.localdomain> <20061011160328.f3e7043a.akpm@osdl.org> From: Andi Kleen Date: 16 Oct 2006 15:48:02 +0200 In-Reply-To: <20061011160328.f3e7043a.akpm@osdl.org> Message-ID: User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton writes: > > Is there any actual need to hold xtime_lock while doing the port IO? I'd > have thought it would suffice to do > > temp = port_io > write_seqlock(xtime_lock); > xtime = muck_with(temp); > write_sequnlock(xtime_lock); > > ? That would be a good idea in general. The trouble is just that whatever race is there will be still there then, just harder to trigger (so instead of every third boot it will muck up every 6 weeks). Not sure that is a real improvement. -Andi