From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763090AbXKIQAW (ORCPT ); Fri, 9 Nov 2007 11:00:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758716AbXKIQAJ (ORCPT ); Fri, 9 Nov 2007 11:00:09 -0500 Received: from ns1.suse.de ([195.135.220.2]:33332 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753196AbXKIQAI (ORCPT ); Fri, 9 Nov 2007 11:00:08 -0500 From: Andi Kleen To: Jeremy Fitzhardinge Subject: Re: Some interesting observations when trying to optimize vmstat handling Date: Fri, 9 Nov 2007 16:56:26 +0100 User-Agent: KMail/1.9.1 Cc: Christoph Lameter , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Mathieu Desnoyers References: <200711090007.43424.ak@suse.de> <4733A7A5.9000900@goop.org> In-Reply-To: <4733A7A5.9000900@goop.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200711091656.26908.ak@suse.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Friday 09 November 2007 01:19, Jeremy Fitzhardinge wrote: > Andi Kleen wrote: > > The only problem is that there might be some code who relies on > > restore_flags() restoring other flags that IF, but at least for > > interrupts and local_irq_save/restore it should be fine to change. > > I don't think so. We don't bother to save/restore the other flags in > Xen paravirt and it doesn't seem to cause a problem. The semantics > really are specific to the state of the interrupt flag. Yes i checked the code and only case I found is actually save_flags, not restore_flags (and that particular case is even unnecessary) -Andi