From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id 445946B008A for ; Mon, 8 Mar 2010 03:34:44 -0500 (EST) Received: from m4.gw.fujitsu.co.jp ([10.0.50.74]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o288YfYK016394 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Mon, 8 Mar 2010 17:34:41 +0900 Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 4AC2845DE60 for ; Mon, 8 Mar 2010 17:34:41 +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 187E845DE6F for ; Mon, 8 Mar 2010 17:34:41 +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 E02F51DB803F for ; Mon, 8 Mar 2010 17:34:40 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.249.87.105]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 600821DB803B for ; Mon, 8 Mar 2010 17:34:40 +0900 (JST) Date: Mon, 8 Mar 2010 17:31:00 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH -mmotm 3/4] memcg: dirty pages accounting and limiting infrastructure Message-Id: <20100308173100.b5997fd4.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100308170711.4d8b02f0.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> <20100308113711.d7a249da.kamezawa.hiroyu@jp.fujitsu.com> <20100308170711.4d8b02f0.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 17:07:11 +0900 Daisuke Nishimura wrote: > On Mon, 8 Mar 2010 11:37:11 +0900, KAMEZAWA Hiroyuki wrote: > > 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. > > > I agree. Performance is my concern too. > > I made a patch below and measured the time(average of 10 times) of kernel build > on tmpfs(make -j8 on 8 CPU machine with 2.6.33 defconfig). > > > - root cgroup: 190.47 sec > - child cgroup: 192.81 sec > > > - root cgroup: 191.06 sec > - child cgroup: 193.06 sec > > Hmm... about 0.3% slower for root, 0.1% slower for child. > Hmm...accepatable ? (sounds it's in error-range) BTW, why local_irq_disable() ? local_irq_save()/restore() isn't better ? Thanks, -Kame > === > From: Daisuke Nishimura > > In current implementation, we don't have to disable irq at lock_page_cgroup() > because the lock is never acquired in interrupt context. > But we are going to do it in later patch, so this patch encloses all of > lock_page_cgroup()/unlock_page_cgroup() with irq_disabled()/irq_enabled(). > > Signed-off-by: Daisuke Nishimura > --- > mm/memcontrol.c | 17 +++++++++++++++++ > 1 files changed, 17 insertions(+), 0 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 02ea959..e5ae1a1 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -1359,6 +1359,7 @@ void mem_cgroup_update_file_mapped(struct page *page, int val) > if (unlikely(!pc)) > return; > > + local_irq_disable(); > lock_page_cgroup(pc); > mem = pc->mem_cgroup; > if (!mem) > @@ -1374,6 +1375,7 @@ void mem_cgroup_update_file_mapped(struct page *page, int val) > > done: > unlock_page_cgroup(pc); > + local_irq_enable(); > } > > /* > @@ -1711,6 +1713,7 @@ struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page) > VM_BUG_ON(!PageLocked(page)); > > pc = lookup_page_cgroup(page); > + local_irq_disable(); > lock_page_cgroup(pc); > if (PageCgroupUsed(pc)) { > mem = pc->mem_cgroup; > @@ -1726,6 +1729,7 @@ struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page) > rcu_read_unlock(); > } > unlock_page_cgroup(pc); > + local_irq_enable(); > return mem; > } > > @@ -1742,9 +1746,11 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *mem, > if (!mem) > return; > > + local_irq_disable(); > lock_page_cgroup(pc); > if (unlikely(PageCgroupUsed(pc))) { > unlock_page_cgroup(pc); > + local_irq_enable(); > mem_cgroup_cancel_charge(mem); > return; > } > @@ -1775,6 +1781,7 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *mem, > mem_cgroup_charge_statistics(mem, pc, true); > > unlock_page_cgroup(pc); > + local_irq_enable(); > /* > * "charge_statistics" updated event counter. Then, check it. > * Insert ancestor (and ancestor's ancestors), to softlimit RB-tree. > @@ -1844,12 +1851,14 @@ static int mem_cgroup_move_account(struct page_cgroup *pc, > struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge) > { > int ret = -EINVAL; > + local_irq_disable(); > lock_page_cgroup(pc); > if (PageCgroupUsed(pc) && pc->mem_cgroup == from) { > __mem_cgroup_move_account(pc, from, to, uncharge); > ret = 0; > } > unlock_page_cgroup(pc); > + local_irq_enable(); > /* > * check events > */ > @@ -1981,12 +1990,15 @@ int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm, > pc = lookup_page_cgroup(page); > if (!pc) > return 0; > + local_irq_disable(); > lock_page_cgroup(pc); > if (PageCgroupUsed(pc)) { > unlock_page_cgroup(pc); > + local_irq_enable(); > return 0; > } > unlock_page_cgroup(pc); > + local_irq_enable(); > } > > if (unlikely(!mm && !mem)) > @@ -2182,6 +2194,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype) > if (unlikely(!pc || !PageCgroupUsed(pc))) > return NULL; > > + local_irq_disable(); > lock_page_cgroup(pc); > > mem = pc->mem_cgroup; > @@ -2222,6 +2235,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype) > > mz = page_cgroup_zoneinfo(pc); > unlock_page_cgroup(pc); > + local_irq_enable(); > > memcg_check_events(mem, page); > /* at swapout, this memcg will be accessed to record to swap */ > @@ -2232,6 +2246,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype) > > unlock_out: > unlock_page_cgroup(pc); > + local_irq_enable(); > return NULL; > } > > @@ -2424,12 +2439,14 @@ int mem_cgroup_prepare_migration(struct page *page, struct mem_cgroup **ptr) > return 0; > > pc = lookup_page_cgroup(page); > + local_irq_disable(); > lock_page_cgroup(pc); > if (PageCgroupUsed(pc)) { > mem = pc->mem_cgroup; > css_get(&mem->css); > } > unlock_page_cgroup(pc); > + local_irq_enable(); > > if (mem) { > ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false); > -- > 1.6.4 > > -- 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