Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756978AbZCWJXu (ORCPT ); Mon, 23 Mar 2009 05:23:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755471AbZCWJXl (ORCPT ); Mon, 23 Mar 2009 05:23:41 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:46996 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754650AbZCWJXk (ORCPT ); Mon, 23 Mar 2009 05:23:40 -0400 From: KOSAKI Motohiro To: KOSAKI Motohiro Subject: Re: [patch 3/3] mm: keep pages from unevictable mappings off the LRU lists Cc: kosaki.motohiro@jp.fujitsu.com, Johannes Weiner , Minchan Kim , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, David Howells , Nick Piggin , Rik van Riel , Peter Zijlstra , Lee Schermerhorn In-Reply-To: <20090323175507.6A18.A69D9226@jp.fujitsu.com> References: <20090323084254.GA1685@cmpxchg.org> <20090323175507.6A18.A69D9226@jp.fujitsu.com> Message-Id: <20090323182039.6A1B.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.50 [ja] Date: Mon, 23 Mar 2009 18:23:36 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1268 Lines: 34 > > > this is the just reason why current code don't call add_page_to_unevictable_list(). > > > add_page_to_unevictable_list() don't use pagevec. it is needed for avoiding race. > > > > > > then, if readahead path (i.e. add_to_page_cache_lru()) use add_page_to_unevictable_list(), > > > it can cause zone->lru_lock contention storm. > > > > How is it different then shrink_page_list()? If readahead put a > > contiguous chunk of unevictable pages to the file lru, then > > shrink_page_list() will as well call add_page_to_unevictable_list() in > > a loop. > > it's probability issue. > > readahead: we need to concern > (1) readahead vs readahead > (2) readahead vs reclaim > > vmscan: we need to concern > (3) background reclaim vs foreground reclaim > > So, (3) is rarely event than (1) and (2). > Am I missing anything? my last mail explanation is too poor. sorry. I don't dislike this patch concept. but it seems a bit naive against contention. if we can decrease contention risk, I can ack with presure. -- 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/