Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934060AbZKXVqg (ORCPT ); Tue, 24 Nov 2009 16:46:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933801AbZKXVqg (ORCPT ); Tue, 24 Nov 2009 16:46:36 -0500 Received: from smtp-out.google.com ([216.239.33.17]:36924 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932690AbZKXVqf (ORCPT ); Tue, 24 Nov 2009 16:46:35 -0500 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=date:from:x-x-sender:to:cc:subject:in-reply-to:message-id: references:user-agent:mime-version:content-type:x-system-of-record; b=V+BpjnRgDPuc/5XsQSg+l9kWGAKIzYY/UkTc5o46noFtKu1kneurXGkuspt3Lxxhw G1i7s56gxEE/5KoXTPn6w== Date: Tue, 24 Nov 2009 13:46:34 -0800 (PST) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Peter Zijlstra cc: Matt Mackall , paulmck@linux.vnet.ibm.com, Pekka Enberg , linux-mm@kvack.org, Christoph Lameter , LKML , Nick Piggin Subject: Re: lockdep complaints in slab allocator In-Reply-To: <1259098552.4531.1857.camel@laptop> Message-ID: References: <84144f020911192249l6c7fa495t1a05294c8f5b6ac8@mail.gmail.com> <1258709153.11284.429.camel@laptop> <84144f020911200238w3d3ecb38k92ca595beee31de5@mail.gmail.com> <1258714328.11284.522.camel@laptop> <4B067816.6070304@cs.helsinki.fi> <1258729748.4104.223.camel@laptop> <1259002800.5630.1.camel@penberg-laptop> <1259003425.17871.328.camel@calx> <4B0ADEF5.9040001@cs.helsinki.fi> <1259080406.4531.1645.camel@laptop> <20091124170032.GC6831@linux.vnet.ibm.com> <1259082756.17871.607.camel@calx> <1259086459.4531.1752.camel@laptop> <1259090615.17871.696.camel@calx> <1259095580.4531.1788.camel@laptop> <1259096004.17871.716.camel@calx> <1259096519.4531.1809.camel@laptop> <1259097150.4531.1822.camel@laptop> <1259098552.4531.1857.camel@laptop> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1827 Lines: 35 On Tue, 24 Nov 2009, Peter Zijlstra wrote: > We should cull something, just merging more and more of them is useless > and wastes everybody's time since you have to add features and > interfaces to all of them. > I agree, but it's difficult to get widespread testing or development interest in an allocator that is sitting outside of mainline. I don't think any allocator could suddenly be merged as the kernel default, it seems like a prerequisite to go through the preliminary merging and development. The severe netperf TCP_RR regression that slub has compared to slab was never found before it became the default allocator, otherwise there would probably have been more effort into its development as well. Unfortunately, slub's design is such that it will probably never be able to nullify the partial slab thrashing enough, even with the percpu counter speedup that is now available because of Christoph's work, to make TCP_RR perform as well as slab. > Then maybe we should toss SLUB? But then there's people who say SLUB is > better for them. Without forcing something to happen we'll be stuck with > multiple allocators forever. > Slub is definitely superior in diagnostics and is a much simpler design than slab. I think it would be much easier to remove slub than slab, though, simply because there are no great slab performance degradations compared to slub. I think the best candidate for removal might be slob, however, because it hasn't been compared to slub and usage may not be as widespread as expected for such a special case allocator. -- 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/