From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753049AbZHBQVw (ORCPT ); Sun, 2 Aug 2009 12:21:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752983AbZHBQVw (ORCPT ); Sun, 2 Aug 2009 12:21:52 -0400 Received: from smtp-outbound-1.vmware.com ([65.115.85.69]:51591 "EHLO smtp-outbound-1.vmware.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752907AbZHBQVv (ORCPT ); Sun, 2 Aug 2009 12:21:51 -0400 Message-ID: <4A75BD2A.9050404@vmware.com> Date: Sun, 02 Aug 2009 18:22:02 +0200 From: =?ISO-8859-1?Q?Thomas_Hellstr=F6m?= User-Agent: Thunderbird 2.0.0.22 (Windows/20090605) MIME-Version: 1.0 To: Pavel Machek 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 References: <1248421981-31865-1-git-send-email-thellstrom@vmware.com> <20090730090747.GD1364@ucw.cz> In-Reply-To: <20090730090747.GD1364@ucw.cz> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Pavel Machek skrev: > On Fri 2009-07-24 09:53:01, Thomas Hellstrom wrote: > >> 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 >> > > You are slowing the kernel down, and you did not write down the > reasons. bad. > > I may slow the kernel down or speed it up depending on your hardware configuration. The reasons should be quite obvious if you read the discussion following the patch. /Thomas