From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id C2DEA8D0001 for ; Fri, 12 Nov 2010 11:22:47 -0500 (EST) Subject: Re: [PATCH/RFC] MM slub: add a sysfs entry to show the calculated number of fallback slabs From: Richard Kennedy In-Reply-To: References: <1289561309.1972.30.camel@castor.rsk> Content-Type: text/plain; charset="UTF-8" Date: Fri, 12 Nov 2010 16:22:44 +0000 Message-ID: <1289578964.1972.43.camel@castor.rsk> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Christoph Lameter Cc: Pekka Enberg , lkml , linux-mm List-ID: On Fri, 2010-11-12 at 09:13 -0600, Christoph Lameter wrote: > On Fri, 12 Nov 2010, Richard Kennedy wrote: > > > On my desktop workloads (kernel compile etc) I'm seeing surprisingly > > little slab fragmentation. Do you have any suggestions for test cases > > that will fragment the memory? > > Do a massive scan through huge amounts of files that triggers inode and > dentry reclaim? thanks, I'll give it a try. > > + * Note that this can give the wrong answer if the user has changed the > > + * order of this slab via sysfs. > > Not good. Maybe have an additional counter in kmem_cache_node instead? I know it's not ideal. Of course there already is a counter in CONFIG_SLUB_STATS but it only counts the total number of fallback slabs issued since boot time. I'm not sure if I can reliably decrement a fallback counter when a slab get freed. If the size was changed then we could have slabs with several different sizes, and off the top of my head I'm not sure if I can identify which ones were created as fallback slabs. I don't suppose there's a spare flag anywhere. I'll give this some more thought. regards Richard -- 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/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org