From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752376AbZGXKFE (ORCPT ); Fri, 24 Jul 2009 06:05:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752216AbZGXKFD (ORCPT ); Fri, 24 Jul 2009 06:05:03 -0400 Received: from one.firstfloor.org ([213.235.205.2]:42216 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752138AbZGXKFC (ORCPT ); Fri, 24 Jul 2009 06:05:02 -0400 To: Thomas Hellstrom Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, venkatesh.pallipadi@intel.com Subject: Re: [PATCH] x86: Use clflush() instead of wbinvd() whenever possible when changing mapping From: Andi Kleen References: <1248421981-31865-1-git-send-email-thellstrom@vmware.com> Date: Fri, 24 Jul 2009 12:05:01 +0200 In-Reply-To: <1248421981-31865-1-git-send-email-thellstrom@vmware.com> (Thomas Hellstrom's message of "Fri, 24 Jul 2009 09:53:01 +0200") Message-ID: <87ocra1jn6.fsf@basil.nowhere.org> User-Agent: Gnus/5.1008 (Gnus v5.10.8) Emacs/22.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Thomas Hellstrom writes: > The current code uses wbinvd() when the area to flush is > 4MB. Although this > may be faster than using clflush() the effect of wbinvd() on irq latencies > may be catastrophical on systems with large caches. Therefore use clflush() may be? You seem to miss some hard data here. I wouldn't expect wbinvd to take longer than a ms or two, which is probably not catastrophic yet. -Andi -- ak@linux.intel.com -- Speaking for myself only.