From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753320Ab2LQSRi (ORCPT ); Mon, 17 Dec 2012 13:17:38 -0500 Received: from mx1.redhat.com ([209.132.183.28]:11476 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752687Ab2LQSRh (ORCPT ); Mon, 17 Dec 2012 13:17:37 -0500 Message-ID: <50CF618C.6020100@redhat.com> Date: Mon, 17 Dec 2012 13:16:44 -0500 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120911 Thunderbird/15.0.1 MIME-Version: 1.0 To: Johannes Weiner CC: Andrew Morton , Michal Hocko , Mel Gorman , Hugh Dickins , Satoru Moriya , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [patch 3/7] mm: vmscan: clarify how swappiness, highest priority, memcg interact References: <1355767957-4913-1-git-send-email-hannes@cmpxchg.org> <1355767957-4913-4-git-send-email-hannes@cmpxchg.org> In-Reply-To: <1355767957-4913-4-git-send-email-hannes@cmpxchg.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/17/2012 01:12 PM, Johannes Weiner wrote: > A swappiness of 0 has a slightly different meaning for global reclaim > (may swap if file cache really low) and memory cgroup reclaim (never > swap, ever). > > In addition, global reclaim at highest priority will scan all LRU > lists equal to their size and ignore other balancing heuristics. > UNLESS swappiness forbids swapping, then the lists are balanced based > on recent reclaim effectiveness. UNLESS file cache is running low, > then anonymous pages are force-scanned. > > This (total mess of a) behaviour is implicit and not obvious from the > way the code is organized. At least make it apparent in the code flow > and document the conditions. It will be it easier to come up with > sane semantics later. > > Signed-off-by: Johannes Weiner Reviewed-by: Rik van Riel -- All rights reversed