From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with SMTP id 5049B6B0044 for ; Thu, 22 Jan 2009 05:01:27 -0500 (EST) Received: by fg-out-1718.google.com with SMTP id 13so2109736fge.4 for ; Thu, 22 Jan 2009 02:01:25 -0800 (PST) MIME-Version: 1.0 In-Reply-To: References: <20090121143008.GV24891@wotan.suse.de> Date: Thu, 22 Jan 2009 12:01:24 +0200 Message-ID: <84144f020901220201g6bdc2d5maf3395fc8b21fe67@mail.gmail.com> Subject: Re: [patch] SLQB slab allocator From: Pekka Enberg Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Hugh Dickins Cc: Nick Piggin , Linux Memory Management List , Linux Kernel Mailing List , Andrew Morton , Lin Ming , "Zhang, Yanmin" , Christoph Lameter List-ID: Hi Hugh, On Wed, Jan 21, 2009 at 8:10 PM, Hugh Dickins wrote: > I was initially _very_ impressed by how well it did on my venerable > tmpfs loop swapping loads, where I'd expected next to no effect; but > that turned out to be because on three machines I'd been using SLUB, > without remembering how default slub_max_order got raised from 1 to 3 > in 2.6.26 (hmm, and Documentation/vm/slub.txt not updated). > > That's been making SLUB behave pretty badly (e.g. elapsed time 30% > more than SLAB) with swapping loads on most of my machines. Though > oddly one seems immune, and another takes four times as long: guess > it depends on how close to thrashing, but probably more to investigate > there. I think my original SLUB versus SLAB comparisons were done on > the immune one: as I remember, SLUB and SLAB were equivalent on those > loads when SLUB came in, but even with boot option slub_max_order=1, > SLUB is still slower than SLAB on such tests (e.g. 2% slower). > FWIW - swapping loads are not what anybody should tune for. What kind of machine are you seeing this on? It sounds like it could be a side-effect from commit 9b2cd506e5f2117f94c28a0040bf5da058105316 ("slub: Calculate min_objects based on number of processors"). Pekka -- 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