Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753217AbXJWUJi (ORCPT ); Tue, 23 Oct 2007 16:09:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752093AbXJWUJc (ORCPT ); Tue, 23 Oct 2007 16:09:32 -0400 Received: from netops-testserver-4-out.sgi.com ([192.48.171.29]:41644 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752062AbXJWUJb (ORCPT ); Tue, 23 Oct 2007 16:09:31 -0400 Date: Tue, 23 Oct 2007 13:09:31 -0700 (PDT) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: Pekka Enberg cc: Alexey Dobriyan , linux-kernel@vger.kernel.org, linux-mm@vger.kernel.org Subject: Re: SLUB 0:1 SLAB (OOM during massive parallel kernel builds) In-Reply-To: <84144f020710231304h6cba8626na4ab4bec0acda7a0@mail.gmail.com> Message-ID: References: <20071023181615.GA10377@martell.zuzino.mipt.ru> <84144f020710231304h6cba8626na4ab4bec0acda7a0@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: 1269 Lines: 27 On Tue, 23 Oct 2007, Pekka Enberg wrote: > On 10/23/07, Christoph Lameter wrote: > > Not sure what this is. Maybe the slowing SLUB solves the race. > > What kind of race are you thinking of? What I initially thought was > that the problem is that SLUB messes up some other VM heuristics due > to different object sizes, not holding on to empty slabs, and/or page > allocator pass-through. I guess only object size is affected by > debugging, though? The number of objects per page is reduced by enabling full debugging. That triggers a potential of more order 1 allocations but we are failing at order 0 allocs. slub_debug=F does not increase object size with debugging information but keeps things as they are while doing as much verification of slab integrity as possible. One--potentially far fetched theory--is that the difference in alloc performance may trigger a race. But I guess it is more likely that we will find something wrong with the gfp flags (that I recategorized for 2.6.24). - 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/