Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 22 Dec 2000 09:28:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 22 Dec 2000 09:28:01 -0500 Received: from d185fcbd7.rochester.rr.com ([24.95.203.215]:29199 "EHLO d185fcbd7.rochester.rr.com") by vger.kernel.org with ESMTP id ; Fri, 22 Dec 2000 09:27:55 -0500 Date: Fri, 22 Dec 2000 08:56:16 -0500 From: Chris Mason To: Marcelo Tosatti , Andreas Dilger cc: "Stephen C. Tweedie" , Alexander Viro , Linus Torvalds , Russell Cattelan , linux-kernel@vger.kernel.org Subject: Re: [RFC] changes to buffer.c (was Test12 ll_rw_block error) Message-ID: <243950000.977493376@coffee> In-Reply-To: X-Mailer: Mulberry/2.0.6b1 (Linux/x86) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thursday, December 21, 2000 22:38:04 -0200 Marcelo Tosatti wrote: > > On Thu, 21 Dec 2000, Andreas Dilger wrote: > >> Marcelo Tosatti writes: >> > It seems your code has a problem with bh flush time. >> > >> > In flush_dirty_buffers(), a buffer may (if being called from kupdate) only >> > be written in case its old enough. (bh->b_flushtime) >> > >> > If the flush happens for an anonymous buffer, you'll end up writing all >> > buffers which are sitting on the same page (with block_write_anon_page), >> > but these other buffers are not necessarily old enough to be flushed. >> >> This isn't really a "problem" however. The page is the _maximum_ age of >> the buffer before it needs to be written. If we can efficiently write it >> out with another buffer > > >> (essentially for free if they are on the same spot on disk) > > Are you sure this is true for buffer pages in most cases? > > It's a good point. block_write_anon_page could be changed to just write the oldest buffer and redirty the page (if the buffers are far apart). If memory is tight, and we *really* need the page back, it will be flushed by try_to_free_buffers. It seems a bit nasty to me though...writepage should write the page. -chris - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/