From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751381AbWDHBBT (ORCPT ); Fri, 7 Apr 2006 21:01:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751383AbWDHBBT (ORCPT ); Fri, 7 Apr 2006 21:01:19 -0400 Received: from mail22.syd.optusnet.com.au ([211.29.133.160]:5540 "EHLO mail22.syd.optusnet.com.au") by vger.kernel.org with ESMTP id S1751381AbWDHBBT (ORCPT ); Fri, 7 Apr 2006 21:01:19 -0400 From: Con Kolivas To: Nick Piggin Subject: Re: [PATCH] mm: limit lowmem_reserve Date: Sat, 8 Apr 2006 11:01:04 +1000 User-Agent: KMail/1.9.1 Cc: Andrew Morton , ck@vds.kolivas.org, linux list , linux-mm@kvack.org References: <200604021401.13331.kernel@kolivas.org> <200604081015.44771.kernel@kolivas.org> <443709F1.90906@yahoo.com.au> In-Reply-To: <443709F1.90906@yahoo.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200604081101.06066.kernel@kolivas.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Saturday 08 April 2006 10:55, Nick Piggin wrote: > Con Kolivas wrote: > > On Friday 07 April 2006 22:40, Nick Piggin wrote: > >>How would zone_watermark_ok always fail though? > > > > Withdrew this patch a while back; ignore > > Well, whether or not that particular patch isa good idea, it > is definitely a bug if zone_watermark_ok could ever always > fail due to lowmem reserve and we should fix it. Ok. I think I presented enough information for why I thought zone_watermark_ok would fail (for ZONE_DMA). With 16MB ZONE_DMA and a vmsplit of 3GB we have a lowmem_reserve of 12MB. It's pretty hard to keep that much ZONE_DMA free, I don't think I've ever seen that much free on my ZONE_DMA on an ordinary desktop without any particular ZONE_DMA users. Changing the tunable can make the lowmem_reserve larger than ZONE_DMA is on any vmsplit too as far as I understand the ratio. -- -ck