From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with ESMTP id 6E92A6B01F1 for ; Thu, 26 Aug 2010 23:31:04 -0400 (EDT) Received: from wpaz24.hot.corp.google.com (wpaz24.hot.corp.google.com [172.24.198.88]) by smtp-out.google.com with ESMTP id o7R3V2Dg032368 for ; Thu, 26 Aug 2010 20:31:02 -0700 Received: from qwk4 (qwk4.prod.google.com [10.241.195.132]) by wpaz24.hot.corp.google.com with ESMTP id o7R3V0CS008255 for ; Thu, 26 Aug 2010 20:31:01 -0700 Received: by qwk4 with SMTP id 4so2155230qwk.9 for ; Thu, 26 Aug 2010 20:31:00 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1282867897-31201-1-git-send-email-yinghan@google.com> Date: Thu, 26 Aug 2010 20:31:00 -0700 Message-ID: Subject: Re: [PATCH] vmscan: fix missing place to check nr_swap_pages. From: Ying Han Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org To: Minchan Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Rik van Riel , KOSAKI Motohiro List-ID: On Thu, Aug 26, 2010 at 6:03 PM, Minchan Kim wrote: > > Hello. > > On Fri, Aug 27, 2010 at 9:11 AM, Ying Han wrote: > > Fix a missed place where checks nr_swap_pages to do shrink_active_list.= Make the > > change that moves the check to common function inactive_anon_is_low. > > > > Hmm.. AFAIR, we discussed it at that time but we concluded it's not good. > That's because nr_swap_pages < 0 means both "NO SWAP" and "NOT enough > swap space now". If we have a swap device or file but not enough space > now, we need to aging anon pages to make inactive list enough size. > Otherwise, working set pages would be swapped out more fast before > promotion. We found the problem on one of our workloads where more TLB flush happens without the change. Kswapd seems to be calling shrink_active_list() which eventually clears access bit of those ptes and does TLB flush with ptep_clear_flush_young(). This system does not have swap configured, and why aging the anon lru in that case? > That aging is done by kswapd so I think it's not big harmful in the syste= m. > But if you want to remove aging completely in non-swap system, we need > to identify non swap system and not enough swap space. I thought we > need it for embedded system. Lots of TLB flush hurts the performance especially on large smp system. So = does it make sense if change it to: + if (nr_swap_pages =3D=3D 0) + return 0; --Ying > Thanks. > > > -- > Kind regards, > Minchan Kim > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. =A0For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org