Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753084Ab2EAUPV (ORCPT ); Tue, 1 May 2012 16:15:21 -0400 Received: from zene.cmpxchg.org ([85.214.230.12]:44619 "EHLO zene.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751165Ab2EAUPT (ORCPT ); Tue, 1 May 2012 16:15:19 -0400 Date: Tue, 1 May 2012 22:15:04 +0200 From: Johannes Weiner To: Andrew Morton Cc: linux-mm@kvack.org, Rik van Riel , Andrea Arcangeli , Peter Zijlstra , Mel Gorman , Minchan Kim , Hugh Dickins , KOSAKI Motohiro , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [patch 2/5] mm + fs: prepare for non-page entries in page cache Message-ID: <20120501201504.GB2112@cmpxchg.org> References: <1335861713-4573-1-git-send-email-hannes@cmpxchg.org> <1335861713-4573-3-git-send-email-hannes@cmpxchg.org> <20120501120246.83d2ce28.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120501120246.83d2ce28.akpm@linux-foundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1286 Lines: 33 On Tue, May 01, 2012 at 12:02:46PM -0700, Andrew Morton wrote: > On Tue, 1 May 2012 10:41:50 +0200 > Johannes Weiner wrote: > > > --- a/fs/inode.c > > +++ b/fs/inode.c > > @@ -544,8 +544,7 @@ static void evict(struct inode *inode) > > if (op->evict_inode) { > > op->evict_inode(inode); > > } else { > > - if (inode->i_data.nrpages) > > - truncate_inode_pages(&inode->i_data, 0); > > + truncate_inode_pages(&inode->i_data, 0); > > Why did we lose this optimisation? For inodes with only shadow pages remaining in the tree, because there is no separate counter for them. Otherwise, we'd leak the tree nodes. I had mapping->nrshadows at first to keep truncation conditional, but thought that using an extra word per cached inode would be worse than removing this optimization. There is not too much being done when the tree is empty. Another solution would be to include the shadows count in ->nrpages, but filesystems use this counter for various other purposes. Do you think it's worth reconsidering? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/