From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id 802FE6B01BE for ; Thu, 27 May 2010 00:24:57 -0400 (EDT) Date: Thu, 27 May 2010 14:24:53 +1000 From: Nick Piggin Subject: Re: [PATCH 3/5] superblock: introduce per-sb cache shrinker infrastructure Message-ID: <20100527042453.GI22536@laptop> References: <1274777588-21494-1-git-send-email-david@fromorbit.com> <1274777588-21494-4-git-send-email-david@fromorbit.com> <20100526164116.GD22536@laptop> <20100526231214.GB1395@dastard> <20100527021905.GG22536@laptop> <20100527040704.GJ12087@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100527040704.GJ12087@dastard> Sender: owner-linux-mm@kvack.org To: Dave Chinner Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, xfs@oss.sgi.com List-ID: On Thu, May 27, 2010 at 02:07:04PM +1000, Dave Chinner wrote: > On Thu, May 27, 2010 at 12:19:05PM +1000, Nick Piggin wrote: > > On Thu, May 27, 2010 at 09:12:14AM +1000, Dave Chinner wrote: > > > On Thu, May 27, 2010 at 02:41:16AM +1000, Nick Piggin wrote: > > > > > + count = ((sb->s_nr_dentry_unused + sb->s_nr_inodes_unused) / 100) > > > > > + * sysctl_vfs_cache_pressure; > > > > > > > > Do you think truncating in the divisions is at all a problem? It > > > > probably doesn't matter much I suppose. > > > > > > Same code as currently exists. IIRC, the reasoning is that if we've > > > got less that 100 objects to reclaim, then we're unlikely to be able > > > to free up any memory from the caches, anyway. > > > > Yeah, which is why I stop short of saying you should change it in > > this patch. > > > > But I think we should ensure things can get reclaimed eventually. > > 100 objects could be 100 slabs, which could be anything from > > half a meg to half a dozen. Multiplied by each of the caches. > > Could be significant in small systems. > > True, but usually there are busy objects in the dentry and inode > slabs, so it shouldn't be a significant issue. We can probably > address such problems if they can be demonstrated to be an issue in > a separate patch set.... I didn't want to say it is a problem with your patchset, I just thought of it when reviewing. -- 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