From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id A48276B00A0 for ; Sun, 4 Oct 2009 08:06:47 -0400 (EDT) Received: by bwz24 with SMTP id 24so1992475bwz.38 for ; Sun, 04 Oct 2009 05:06:45 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1253624054-10882-1-git-send-email-mel@csn.ul.ie> <1253624054-10882-3-git-send-email-mel@csn.ul.ie> <84144f020909220638l79329905sf9a35286130e88d0@mail.gmail.com> <20090922135453.GF25965@csn.ul.ie> <84144f020909221154x820b287r2996480225692fad@mail.gmail.com> <20090922185608.GH25965@csn.ul.ie> <20090930144117.GA17906@csn.ul.ie> <20090930220541.GA31530@csn.ul.ie> Date: Sun, 4 Oct 2009 15:06:45 +0300 Message-ID: <84144f020910040506l24a74660s508c828123c554cc@mail.gmail.com> Subject: Re: [PATCH 2/4] slqb: Record what node is local to a kmem_cache_cpu From: Pekka Enberg Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org To: Christoph Lameter Cc: Mel Gorman , Nick Piggin , heiko.carstens@de.ibm.com, sachinp@in.ibm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Tejun Heo , Benjamin Herrenschmidt List-ID: On Thu, Oct 1, 2009 at 2:45 AM, Christoph Lameter wrote: >> This is essentially the "unqueued" nature of SLUB. It's objective "I have this >> page here which I'm going to use until I can't use it no more and will depend >> on the page allocator to sort my stuff out". I have to read up on SLUB up >> more to see if it's compatible with SLQB or not though. In particular, how >> does SLUB deal with frees from pages that are not the "current" page? SLQB >> does not care what page the object belongs to as long as it's node-local >> as the object is just shoved onto a LIFO for maximum hotness. > > Frees are done directly to the target slab page if they are not to the > current active slab page. No centralized locks. Concurrent frees from > processors on the same node to multiple other nodes (or different pages > on the same node) can occur. > >> > SLAB deals with it in fallback_alloc(). It scans the nodes in zonelist >> > order for free objects of the kmem_cache and then picks up from the >> > nearest node. Ugly but it works. SLQB would have to do something similar >> > since it also has the per node object bins that SLAB has. >> > >> >> In a real sense, this is what the patch ends up doing. When it fails to >> get something locally but sees that the local node is memoryless, it >> will check the remote node lists in zonelist order. I think that's >> reasonable behaviour but I'm biased because I just want the damn machine >> to boot again. What do you think? Pekka, Nick? > > Look at fallback_alloc() in slab. You can likely copy much of it. It > considers memory policies and cpuset constraints. Sorry for the delay. I went ahead and merged Mel's patch to make things boot on PPC. Fallback policy needs a bit more work as Christoph says but I'd really love to have Nick's input on this. Mel, do you have a Kconfig patch laying around somewhere to enable SLQB on PPC and S390? 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