From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932148AbWDFEgg (ORCPT ); Thu, 6 Apr 2006 00:36:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932151AbWDFEgg (ORCPT ); Thu, 6 Apr 2006 00:36:36 -0400 Received: from mail16.syd.optusnet.com.au ([211.29.132.197]:17057 "EHLO mail16.syd.optusnet.com.au") by vger.kernel.org with ESMTP id S932148AbWDFEgf (ORCPT ); Thu, 6 Apr 2006 00:36:35 -0400 From: Con Kolivas To: Andrew Morton Subject: Re: Respin: [PATCH] mm: limit lowmem_reserve Date: Thu, 6 Apr 2006 14:36:16 +1000 User-Agent: KMail/1.9.1 Cc: ck@vds.kolivas.org, nickpiggin@yahoo.com.au, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <200604021401.13331.kernel@kolivas.org> <200604061258.40487.kernel@kolivas.org> <20060405204009.3235b021.akpm@osdl.org> In-Reply-To: <20060405204009.3235b021.akpm@osdl.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200604061436.16907.kernel@kolivas.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 06 April 2006 13:40, Andrew Morton wrote: > Con Kolivas wrote: > > On Thursday 06 April 2006 12:55, Con Kolivas wrote: > > > On Thursday 06 April 2006 12:43, Andrew Morton wrote: > > > > Con Kolivas wrote: > > > > > It is possible with a low enough lowmem_reserve ratio to make > > > > > zone_watermark_ok fail repeatedly if the lower_zone is small > > > > > enough. > > > > > > > > Is that actually a problem? > > > > > > Every single call to get_page_from_freelist will call on zone reclaim. > > > It seems a problem to me if every call to __alloc_pages will do that? > > > > every call to __alloc_pages of that zone I mean > > One would need to check with the NUMA guys. zone_reclaim() has a > (lame-looking) timer in there to prevent it from doing too much work. > > That, or I'm missing something. This problem wasn't particularly well > described, sorry. Ah ok. This all came about because I'm trying to honour the lowmem_reserve better in swap_prefetch at Nick's request. It's hard to honour a watermark that on some configurations is never reached. Cheers, Con