Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759586AbXKCTKo (ORCPT ); Sat, 3 Nov 2007 15:10:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756542AbXKCTKg (ORCPT ); Sat, 3 Nov 2007 15:10:36 -0400 Received: from extu-mxob-1.symantec.com ([216.10.194.28]:34697 "EHLO extu-mxob-1.symantec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755741AbXKCTKg (ORCPT ); Sat, 3 Nov 2007 15:10:36 -0400 Date: Sat, 3 Nov 2007 19:09:57 +0000 (GMT) From: Hugh Dickins X-X-Sender: hugh@blonde.wat.veritas.com To: Christoph Lameter cc: Linus Torvalds , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] slub: fix Objects count In-Reply-To: Message-ID: References: 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: 1213 Lines: 32 On Sat, 3 Nov 2007, Christoph Lameter wrote: > On Sat, 3 Nov 2007, Hugh Dickins wrote: > > > The count of active Objects shown by Slub's slabinfo is too approximate, > > because each cpu slab is counted as all in use, even when lots are free. > > That makes tracing leaks harder than it need be. > > True but that is the way it is for performance reasons. I was afraid you might say something like that. Perhaps it'll be a patch I need to use in my own builds. Though I'd have thought others would want that accuracy too. Didn't SLAB give it? (The "r*gr*ss**n" word!) > > Add a free count into kmem_cache_cpu (which doesn't enlarge it on 64-bit), > > to keep that count in the hot and dirty per-cpu cacheline. > > Adds to much overhead to the fast paths You've come to that conclusion very quickly! Any numbers to back it up? > and will make the current optimizations in mm impossible. I'll have to wait and see what those are: you move too fast for me. Hugh - 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/