From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751693AbaDASbp (ORCPT ); Tue, 1 Apr 2014 14:31:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:63887 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751627AbaDASbo (ORCPT ); Tue, 1 Apr 2014 14:31:44 -0400 Message-ID: <533B0603.7040301@redhat.com> Date: Tue, 01 Apr 2014 14:31:31 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: Linus Torvalds CC: Linux Kernel Mailing List , linux-mm , shli@kernel.org, Andrew Morton , Ingo Molnar , Hugh Dickins , Mel Gorman Subject: Re: [PATCH] x86,mm: delay TLB flush after clearing accessed bit References: <20140331113442.0d628362@annuminas.surriel.com> <533AE518.1090705@redhat.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/01/2014 12:21 PM, Linus Torvalds wrote: > On Tue, Apr 1, 2014 at 9:11 AM, Rik van Riel wrote: >> >> Memory pressure is not necessarily caused by the same process >> whose accessed bit we just cleared. Memory pressure may not >> even be caused by any process's virtual memory at all, but it >> could be caused by the page cache. > > If we have that much memory pressure on the page cache without having > any memory pressure on the actual VM space, then the swap-out activity > will never be an issue anyway. > > IOW, I think all these scenarios are made-up. I'd much rather go for > simpler implementation, and make things more complex only in the > presence of numbers. Of which we have none. We've been bitten by the lack of a properly tracked accessed bit before, but admittedly that was with the KVM code and EPT. I'll add my Acked-by: to Shaohua's original patch then, and will keep my eyes open for any problems that may or may not materialize... Shaohua? -- All rights reversed