From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754373Ab1HVXXD (ORCPT ); Mon, 22 Aug 2011 19:23:03 -0400 Received: from ipmail06.adl2.internode.on.net ([150.101.137.129]:33035 "EHLO ipmail06.adl2.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753950Ab1HVXXB (ORCPT ); Mon, 22 Aug 2011 19:23:01 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Av0EAC/iUk55LIxD/2dsb2JhbABBqB54gUABAQU6HCMQCAMYLhQlAyETvUAOhjoEpB0 Date: Tue, 23 Aug 2011 09:22:57 +1000 From: Dave Chinner To: Konstantin Khlebnikov Cc: linux-mm@kvack.org, Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] vmscan: fix initial shrinker size handling Message-ID: <20110822232257.GT3162@dastard> References: <20110822101721.19462.63082.stgit@zurg> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110822101721.19462.63082.stgit@zurg> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 22, 2011 at 02:17:21PM +0300, Konstantin Khlebnikov wrote: > Shrinker function can returns -1, it means it cannot do anything without a risk of deadlock. > For example prune_super() do this if it cannot grab superblock refrence, even if nr_to_scan=0. > Currenly we interpret this like ULONG_MAX size shrinker, evaluate total_scan according this, > and next time this shrinker can get really big pressure. Let's skip such shrinkers instead. > > Also make total_scan signed, otherwise check (total_scan < 0) below never works. I've got a patch set I am going to post out today that makes this irrelevant. The patch set splits the shrinker api into 2 callbacks - a "count objects" callback and an "scan objects" callback, getting rid of this messy "pass nr-to_scan == 0 to count objects" wart altogether. Cheers, Dave. -- Dave Chinner david@fromorbit.com