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 8265E6B0212 for ; Sun, 4 Apr 2010 20:36:01 -0400 (EDT) Received: by pwi2 with SMTP id 2so2497929pwi.14 for ; Sun, 04 Apr 2010 17:36:00 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20100404181550.GA2350@ioremap.net> References: <1270396784.1814.92.camel@barrios-desktop> <20100404160328.GA30540@ioremap.net> <1270398112.1814.114.camel@barrios-desktop> <20100404181550.GA2350@ioremap.net> Date: Mon, 5 Apr 2010 09:36:00 +0900 Message-ID: Subject: Re: why are some low-level MM routines being exported? From: Minchan Kim Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org To: Evgeniy Polyakov Cc: "Robert P. J. Day" , linux-mm@kvack.org, Joern Engel List-ID: On Mon, Apr 5, 2010 at 3:15 AM, Evgeniy Polyakov wrote: > On Mon, Apr 05, 2010 at 01:21:52AM +0900, Minchan Kim (minchan.kim@gmail.com) wrote: >> > > It is added by 18bc0bbd162e3 for pohmelfs and now used by logfs, too. >> > > I didn't noticed that at that time. >> > > With git log, any mm guys didn't add Signed-off-by or Reviewed-by. >> > > >> > > I think it's not good for file system or module to use it directly. >> > > It would make LRU management harder. >> > >> > How come? >> >> What I have a concern is that if file systems or some modules start to >> overuse it to manage pages LRU directly, some mistake of them would make >> system global LRU stupid and make system wrong. > > All filesystems already call it through find_or_create_page() or > grab_page() invoked via read path. In some cases fs has more than > one page grabbed via its internal path where data to be read is > already placed, so it may want just to add those pages into mm lru. > I understood why it does need that in pohmelfs. AFAIU, other file system using general functions(ex, mpage_readpages or read_cache_pages) don't need direct LRU handling since it's hided. But pohmelfs doesn't use general functions. Isn't pagevec_lru_add_file enough like other file system(ex, nfs, cifs)? -- 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/ . Don't email: email@kvack.org