Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750773AbWABPrE (ORCPT ); Mon, 2 Jan 2006 10:47:04 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750776AbWABPrE (ORCPT ); Mon, 2 Jan 2006 10:47:04 -0500 Received: from mail.fh-wedel.de ([213.39.232.198]:24801 "EHLO moskovskaya.fh-wedel.de") by vger.kernel.org with ESMTP id S1750773AbWABPrC (ORCPT ); Mon, 2 Jan 2006 10:47:02 -0500 Date: Mon, 2 Jan 2006 16:46:48 +0100 From: =?iso-8859-1?Q?J=F6rn?= Engel To: Andi Kleen Cc: Pekka J Enberg , Denis Vlasenko , Eric Dumazet , linux-kernel@vger.kernel.org Subject: Re: [POLL] SLAB : Are the 32 and 192 bytes caches really usefull on x86_64 machines ? Message-ID: <20060102154648.GB673@wohnheim.fh-wedel.de> References: <7vbqzadgmt.fsf@assigned-by-dhcp.cox.net> <200601021345.44843.ak@suse.de> <200601021456.23253.ak@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <200601021456.23253.ak@suse.de> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1327 Lines: 32 On Mon, 2 January 2006 14:56:22 +0100, Andi Kleen wrote: > > I wasn't proposing fully dynamic slabs, just a better default set > of slabs based on real measurements instead of handwaving (like > the power of two slabs seemed to have been generated). With separate > sets for 32bit and 64bit. > > Also the goal wouldn't be better performance, but just less waste of memory. My fear would be that this leads to something like the gperf: a perfect distribution of slab caches - until any tiny detail changes. But maybe there is a different distribution that is "pretty good" for all configurations and better than powers of two. > I suspect such a move could save much more memory on small systems > than any of these "make fundamental debugging tools a CONFIG" patches ever. Unlikely. SLOB should be better than SLAB for those purposes, no matter how you arrange the slab caches. J?rn -- Fancy algorithms are slow when n is small, and n is usually small. Fancy algorithms have big constants. Until you know that n is frequently going to be big, don't get fancy. -- Rob Pike - 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/