Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758606Ab3FCPVM (ORCPT ); Mon, 3 Jun 2013 11:21:12 -0400 Received: from zene.cmpxchg.org ([85.214.230.12]:46320 "EHLO zene.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756567Ab3FCPVK (ORCPT ); Mon, 3 Jun 2013 11:21:10 -0400 Date: Mon, 3 Jun 2013 11:20:32 -0400 From: Johannes Weiner To: Peter Zijlstra Cc: linux-mm@kvack.org, Andi Kleen , Andrea Arcangeli , Andrew Morton , Greg Thelen , Christoph Hellwig , Hugh Dickins , Jan Kara , KOSAKI Motohiro , Mel Gorman , Minchan Kim , Rik van Riel , Michel Lespinasse , Seth Jennings , Roman Gushchin , metin d , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [patch 10/10] mm: workingset: keep shadow entries in check Message-ID: <20130603152032.GF15576@cmpxchg.org> References: <1369937046-27666-1-git-send-email-hannes@cmpxchg.org> <1369937046-27666-11-git-send-email-hannes@cmpxchg.org> <20130603082533.GH5910@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130603082533.GH5910@twins.programming.kicks-ass.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1425 Lines: 25 On Mon, Jun 03, 2013 at 10:25:33AM +0200, Peter Zijlstra wrote: > On Thu, May 30, 2013 at 02:04:06PM -0400, Johannes Weiner wrote: > > Previously, page cache radix tree nodes were freed after reclaim > > emptied out their page pointers. But now reclaim stores shadow > > entries in their place, which are only reclaimed when the inodes > > themselves are reclaimed. This is problematic for bigger files that > > are still in use after they have a significant amount of their cache > > reclaimed, without any of those pages actually refaulting. The shadow > > entries will just sit there and waste memory. In the worst case, the > > shadow entries will accumulate until the machine runs out of memory. > > > > Can't we simply prune all refault entries that have a distance larger > than the memory size? Then we must assume that no refault entry means > its too old, which I think is a fair assumption. Two workloads bound to two nodes might not push pages through the LRUs at the same pace, so a distance might be bigger than memory due to the faster moving node, yet still be a hit in the slower moving one. We can't really know until we evaluate it on a per-zone basis. -- 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/