From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx182.postini.com [74.125.245.182]) by kanga.kvack.org (Postfix) with SMTP id 671146B0044 for ; Tue, 1 May 2012 16:15:14 -0400 (EDT) Date: Tue, 1 May 2012 22:15:04 +0200 From: Johannes Weiner 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: owner-linux-mm@kvack.org List-ID: 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 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, 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 internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org