From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id C0C9F6B0044 for ; Mon, 26 Jan 2009 12:26:07 -0500 (EST) Received: from localhost (smtp.ultrahosting.com [127.0.0.1]) by smtp.ultrahosting.com (Postfix) with ESMTP id 14B3982C25C for ; Mon, 26 Jan 2009 12:27:47 -0500 (EST) Received: from smtp.ultrahosting.com ([74.213.174.254]) by localhost (smtp.ultrahosting.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id NZOuEV3KQ7Ln for ; Mon, 26 Jan 2009 12:27:47 -0500 (EST) Received: from qirst.com (unknown [74.213.171.31]) by smtp.ultrahosting.com (Postfix) with ESMTP id 2CACD82C25D for ; Mon, 26 Jan 2009 12:27:40 -0500 (EST) Date: Mon, 26 Jan 2009 12:22:28 -0500 (EST) From: Christoph Lameter Subject: Re: [patch] SLQB slab allocator (try 2) In-Reply-To: <1232960840.4863.7.camel@laptop> Message-ID: References: <20090123154653.GA14517@wotan.suse.de> <1232959706.21504.7.camel@penberg-laptop> <1232960840.4863.7.camel@laptop> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Peter Zijlstra Cc: Pekka Enberg , Nick Piggin , Linux Memory Management List , Linux Kernel Mailing List , Andrew Morton , Lin Ming , "Zhang, Yanmin" List-ID: On Mon, 26 Jan 2009, Peter Zijlstra wrote: > Then again, anything that does allocation is per definition not bounded > and not something we can have on latency critical paths -- so on that > respect its not interesting. Well there is the problem in SLAB and SLQB that they *continue* to do processing after an allocation. They defer queue cleaning. So your latency critical paths are interrupted by the deferred queue processing. SLAB has the awful habit of gradually pushing objects out of its queued (tried to approximate the loss of cpu cache hotness over time). So for awhile you get hit every 2 seconds with some free operations to the page allocator on each cpu. If you have a lot of cpus then this may become an ongoing operation. The slab pages end up in the page allocator queues which is then occasionally pushed back to the buddy lists. Another relatively high spike there. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org