From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Pekka Enberg" Subject: Re: Mainline kernel OLTP performance update Date: Mon, 19 Jan 2009 11:48:52 +0200 Message-ID: <84144f020901190148r7ea135b6uead33842e93e59c2@mail.gmail.com> References: <200901191813.07960.nickpiggin@yahoo.com.au> <1232352303.30141.25.camel@penberg-laptop> <200901191933.29322.nickpiggin@yahoo.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from fg-out-1718.google.com ([72.14.220.158]:18340 "EHLO fg-out-1718.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753852AbZASJsy (ORCPT ); Mon, 19 Jan 2009 04:48:54 -0500 In-Reply-To: <200901191933.29322.nickpiggin@yahoo.com.au> Content-Disposition: inline Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Nick Piggin Cc: Matthew Wilcox , Andrew Morton , "Wilcox, Matthew R" , chinang.ma@intel.com, linux-kernel@vger.kernel.org, sharad.c.tripathi@intel.com, arjan@linux.intel.com, andi.kleen@intel.com, suresh.b.siddha@intel.com, harita.chilukuri@intel.com, douglas.w.styner@intel.com, peter.xihong.wang@intel.com, hubert.nueckel@intel.com, chris.mason@oracle.com, srostedt@redhat.com, linux-scsi@vger.kernel.org, Andrew Vasquez , Anirban Chakraborty , Christoph Lameter Hi Nick, On Mon, Jan 19, 2009 at 10:33 AM, Nick Piggin wrote: >> All I am saying is that I don't like how we're fixing a performance bug >> with a shiny new allocator without a credible explanation why the >> current approach is not fixable. > > To be honest, my biggest concern with SLUB is the higher order pages > thing. But Christoph always poo poos me when I raise that concern, and > it's hard to get concrete numbers showing real fragmentation problems > when it can take days or months to start biting. To be fair to SLUB, we do have the pending slab defragmentation patches in my tree. Not that we have any numbers on if defragmentation helps and how much. IIRC, Christoph said one of the reasons for avoiding queues in SLUB is to be able to do defragmentation. But I suppose with SLQB we can do the same thing as long as we flush the queues before attempting to defrag. Pekka