Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757414AbZCWJBk (ORCPT ); Mon, 23 Mar 2009 05:01:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756964AbZCWJBR (ORCPT ); Mon, 23 Mar 2009 05:01:17 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:51657 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756383AbZCWJBQ (ORCPT ); Mon, 23 Mar 2009 05:01:16 -0400 From: KOSAKI Motohiro To: Johannes Weiner Subject: Re: [patch 3/3] mm: keep pages from unevictable mappings off the LRU lists Cc: kosaki.motohiro@jp.fujitsu.com, 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: <20090323084254.GA1685@cmpxchg.org> References: <20090323111615.69F3.A69D9226@jp.fujitsu.com> <20090323084254.GA1685@cmpxchg.org> Message-Id: <20090323175507.6A18.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 18:01:07 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1519 Lines: 44 > On Mon, Mar 23, 2009 at 11:21:36AM +0900, KOSAKI Motohiro wrote: > > > Hmm,, > > > > > > This patch is another thing unlike previous series patches. > > > Firstly, It looked good to me. > > > > > > I think add_to_page_cache_lru have to become a fast path. > > > But, how often would ramfs and shmem function be called ? > > > > > > I have a concern for this patch to add another burden. > > > so, we need any numbers for getting pros and cons. > > > > > > Any thoughts ? > > > > 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? -- 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/