From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id E21796B0047 for ; Sun, 7 Mar 2010 21:40:56 -0500 (EST) Received: from m4.gw.fujitsu.co.jp ([10.0.50.74]) by fgwmail7.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o282es0r019199 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Mon, 8 Mar 2010 11:40:54 +0900 Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 8F7EC45DE7E for ; Mon, 8 Mar 2010 11:40:54 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 62D7945DE6F for ; Mon, 8 Mar 2010 11:40:54 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 3E1391DB8037 for ; Mon, 8 Mar 2010 11:40:54 +0900 (JST) Received: from ml13.s.css.fujitsu.com (ml13.s.css.fujitsu.com [10.249.87.103]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id B756F1DB803A for ; Mon, 8 Mar 2010 11:40:53 +0900 (JST) Date: Mon, 8 Mar 2010 11:37:11 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH -mmotm 3/4] memcg: dirty pages accounting and limiting infrastructure Message-Id: <20100308113711.d7a249da.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100308111724.3e48aee3.nishimura@mxp.nes.nec.co.jp> References: <1267995474-9117-1-git-send-email-arighi@develer.com> <1267995474-9117-4-git-send-email-arighi@develer.com> <20100308104447.c124c1ff.nishimura@mxp.nes.nec.co.jp> <20100308105641.e2e714f4.kamezawa.hiroyu@jp.fujitsu.com> <20100308111724.3e48aee3.nishimura@mxp.nes.nec.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Daisuke Nishimura Cc: Andrea Righi , Balbir Singh , Vivek Goyal , Peter Zijlstra , Trond Myklebust , Suleiman Souhlal , Greg Thelen , "Kirill A. Shutemov" , Andrew Morton , containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Mon, 8 Mar 2010 11:17:24 +0900 Daisuke Nishimura wrote: > > But IIRC, clear_writeback is done under treelock.... No ? > > > The place where NR_WRITEBACK is updated is out of tree_lock. > > 1311 int test_clear_page_writeback(struct page *page) > 1312 { > 1313 struct address_space *mapping = page_mapping(page); > 1314 int ret; > 1315 > 1316 if (mapping) { > 1317 struct backing_dev_info *bdi = mapping->backing_dev_info; > 1318 unsigned long flags; > 1319 > 1320 spin_lock_irqsave(&mapping->tree_lock, flags); > 1321 ret = TestClearPageWriteback(page); > 1322 if (ret) { > 1323 radix_tree_tag_clear(&mapping->page_tree, > 1324 page_index(page), > 1325 PAGECACHE_TAG_WRITEBACK); > 1326 if (bdi_cap_account_writeback(bdi)) { > 1327 __dec_bdi_stat(bdi, BDI_WRITEBACK); > 1328 __bdi_writeout_inc(bdi); > 1329 } > 1330 } > 1331 spin_unlock_irqrestore(&mapping->tree_lock, flags); > 1332 } else { > 1333 ret = TestClearPageWriteback(page); > 1334 } > 1335 if (ret) > 1336 dec_zone_page_state(page, NR_WRITEBACK); > 1337 return ret; > 1338 } We can move this up to under tree_lock. Considering memcg, all our target has "mapping". If we newly account bounce-buffers (for NILFS, FUSE, etc..), which has no ->mapping, we need much more complex new charge/uncharge theory. But yes, adding new lock scheme seems complicated. (Sorry Andrea.) My concerns is performance. We may need somehing new re-implementation of locks/migrate/charge/uncharge. Thanks, -Kame -- 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