From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [PATCH 08/10] mm: count writeback pages per BDI From: Peter Zijlstra In-Reply-To: <20070422001949.4d697fe5.akpm@linux-foundation.org> References: <20070420155154.898600123@chello.nl> <20070420155503.334628394@chello.nl> <20070421025525.042ed73a.akpm@linux-foundation.org> <1177153636.2934.43.camel@lappy> <20070422001949.4d697fe5.akpm@linux-foundation.org> Content-Type: text/plain Date: Sun, 22 Apr 2007 11:08:52 +0200 Message-Id: <1177232932.7316.67.camel@twins> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, miklos@szeredi.hu, neilb@suse.de, dgc@sgi.com, tomoki.sekiyama.qu@hitachi.com, nikita@clusterfs.com, trond.myklebust@fys.uio.no, yingchao.zhou@gmail.com List-ID: On Sun, 2007-04-22 at 00:19 -0700, Andrew Morton wrote: > It could be that we never call test_clear_page_writeback() against > !bdi_cap_writeback_dirty() pages anwyay. I can't think why we would, but > the relationships there aren't very clear. Does "don't account for dirty > memory" imply "doesn't ever do writeback"? One would need to check, and > it's perhaps a bit fragile. I did, thats how that test ended up there; I guess a comment would have been a good thing, no? :-) end_swap_bio_write() calls end_page_writeback(), and swap_backing_dev_info has neither cap_writeback nor cap_account_dirty. > It's worth checking though. Boy we're doing a lot of stuff in there > nowadays. > > OT: it might be worth looking into batching this work up - the predominant > caller should be mpage_end_io_write(), and he has a whole bunch of pages > which are usually all from the same file, all contiguous. It's pretty > inefficient to be handling that data one-page-at-a-time, and some > significant speedups may be available. Right, that might be a good spot to hook into, I'll have a look. > Instead, everyone seems to think that variable pagecache page size is the > only way of improving things. Shudder. hehe, I guess you haven't looked at my concurrent pagecache patches yet either :-) -- 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