Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932319AbXHJRqm (ORCPT ); Fri, 10 Aug 2007 13:46:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754858AbXHJRqe (ORCPT ); Fri, 10 Aug 2007 13:46:34 -0400 Received: from netops-testserver-4-out.sgi.com ([192.48.171.29]:36812 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754445AbXHJRqd (ORCPT ); Fri, 10 Aug 2007 13:46:33 -0400 Date: Fri, 10 Aug 2007 10:46:30 -0700 (PDT) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: Daniel Phillips cc: Daniel Phillips , Peter Zijlstra , Matt Mackall , linux-kernel@vger.kernel.org, linux-mm@kvack.org, David Miller , Andrew Morton , Daniel Phillips Subject: Re: [PATCH 02/10] mm: system wide ALLOC_NO_WATERMARK In-Reply-To: <4a5909270708100115v4ad10c4es697d216edf29b07d@mail.gmail.com> Message-ID: References: <20070806102922.907530000@chello.nl> <4a5909270708080037n32be2a73k5c28d33bb02f770b@mail.gmail.com> <4a5909270708091141tb259eddyb2bba1270751ef1@mail.gmail.com> <4a5909270708091717n2f93fcb5i284d82edfd235145@mail.gmail.com> <4a5909270708092034yaa0a583w70084ef93266df48@mail.gmail.com> <4a5909270708100115v4ad10c4es697d216edf29b07d@mail.gmail.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1496 Lines: 31 On Fri, 10 Aug 2007, Daniel Phillips wrote: > It is quite clear what is in your patch. Instead of just grabbing a > page off the buddy free lists in a critical allocation situation you > go invoke shrink_caches. Why oh why? All the memory needed to get Because we get to the code of interest when we have no memory on the buddy free lists and need to reclaim memory to fill them up again. > You do not do anything to prevent mixing of ordinary slab allocations > of unknown duration with critical allocations of controlled duration. > This is _very important_ for sk_alloc. How are you going to take > care of that? It is not necessary because you can reclaim memory as needed. > There are certainly improvements that can be made to the posted patch > set. Running off and learning from scratch how to do this is not > really helpful. The idea of adding code to deal with "I have no memory" situations in a kernel that based on have as much memory as possible in use at all times is plainly the wrong approach. If you need memory then memory needs to be reclaimed. That is the basic way that things work and following that through brings about a much less invasive solution without all the issues that the proposed solution creates. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/