From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id 17B4C6B004A for ; Mon, 29 Nov 2010 03:26:57 -0500 (EST) Date: Mon, 29 Nov 2010 16:26:51 +0800 From: Wu Fengguang Subject: Re: [PATCH v2 2/3] move ClearPageReclaim Message-ID: <20101129082651.GA26715@localhost> References: <7b50614882592047dfd96f6ca2bb2d0baa8f5367.1290956059.git.minchan.kim@gmail.com> <20101129072951.GA22803@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: owner-linux-mm@kvack.org To: Minchan Kim Cc: Andrew Morton , linux-mm , LKML , Ben Gamari , Rik van Riel , KOSAKI Motohiro , Johannes Weiner , Nick Piggin , Mel Gorman List-ID: On Mon, Nov 29, 2010 at 04:16:01PM +0800, Minchan Kim wrote: > On Mon, Nov 29, 2010 at 4:29 PM, Wu Fengguang wrote: > > On Sun, Nov 28, 2010 at 11:02:56PM +0800, Minchan Kim wrote: > >> fe3cba17 added ClearPageReclaim into clear_page_dirty_for_io for > >> preventing fast reclaiming readahead marker page. > >> > >> In this series, PG_reclaim is used by invalidated page, too. > >> If VM find the page is invalidated and it's dirty, it sets PG_reclaim > >> to reclaim asap. Then, when the dirty page will be writeback, > >> clear_page_dirty_for_io will clear PG_reclaim unconditionally. > >> It disturbs this serie's goal. > >> > >> I think it's okay to clear PG_readahead when the page is dirty, not > >> writeback time. So this patch moves ClearPageReadahead. > >> This patch needs Wu's opinion. > > > > It's a safe change. The possibility and consequence of races are both > > small enough. However the patch could be simplified as follows? > > If all of file systems use it, I don't mind it. > Do all of filesystems use it when the page is dirtied? > I was not sure it.(It's why I added Cc. :) > If it doesn't have a problem, I hope so. Please double check, but here is my findings: __set_page_dirty_buffers() is called by several fs' ->set_page_dirty() which are all called by set_page_dirty(). set_page_dirty_lock() will call set_page_dirty(). __set_page_dirty_no_writeback(): it have no connection to end_page_writeback(), so no need to set PG_reclaim. Thanks, Fengguang > > --- linux-next.orig/mm/page-writeback.c 2010-11-29 15:14:54.000000000 +0800 > > +++ linux-next/mm/page-writeback.c A A A 2010-11-29 15:15:02.000000000 +0800 > > @@ -1330,6 +1330,7 @@ int set_page_dirty(struct page *page) > > A { > > A A A A struct address_space *mapping = page_mapping(page); > > > > + A A A ClearPageReclaim(page); > > A A A A if (likely(mapping)) { > > A A A A A A A A int (*spd)(struct page *) = mapping->a_ops->set_page_dirty; > > A #ifdef CONFIG_BLOCK > > @@ -1387,7 +1388,6 @@ int clear_page_dirty_for_io(struct page > > > > A A A A BUG_ON(!PageLocked(page)); > > > > - A A A ClearPageReclaim(page); > > A A A A if (mapping && mapping_cap_account_dirty(mapping)) { > > A A A A A A A A /* > > A A A A A A A A * Yes, Virginia, this is indeed insane. > > > > > > -- > Kind regards, > Minchan Kim -- 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 policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org