From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fengguang Wu Subject: Re: [PATCH 6/7] memcg: add per cgroup writeback pages accounting Date: Mon, 9 Jul 2012 12:14:37 +0800 Message-ID: <20120709041437.GA10180@localhost> References: <1340880885-5427-1-git-send-email-handai.szj@taobao.com> <1340881562-5900-1-git-send-email-handai.szj@taobao.com> <20120708145309.GC18272@localhost> <4FFA51AB.30203@gmail.com> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <4FFA51AB.30203-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Sha Zhengju Cc: linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org, gthelen-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, yinghan-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, mhocko-AlSwsSmVLrQ@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Sha Zhengju On Mon, Jul 09, 2012 at 11:36:11AM +0800, Sha Zhengju wrote: > On 07/08/2012 10:53 PM, Fengguang Wu wrote: > >>@@ -2245,7 +2252,10 @@ int test_set_page_writeback(struct page *page) > >> { > >> struct address_space *mapping = page_mapping(page); > >> int ret; > >>+ bool locked; > >>+ unsigned long flags; > >> > >>+ mem_cgroup_begin_update_page_stat(page,&locked,&flags); > >> if (mapping) { > >> struct backing_dev_info *bdi = mapping->backing_dev_info; > >> unsigned long flags; > >>@@ -2272,6 +2282,8 @@ int test_set_page_writeback(struct page *page) > >> } > >> if (!ret) > >> account_page_writeback(page); > >>+ > >>+ mem_cgroup_end_update_page_stat(page,&locked,&flags); > >> return ret; > >> > >> } > >Where is the MEM_CGROUP_STAT_FILE_WRITEBACK increased? > > > > It's in account_page_writeback(). > > void account_page_writeback(struct page *page) > { > + mem_cgroup_inc_page_stat(page, MEM_CGROUP_STAT_FILE_WRITEBACK); > inc_zone_page_state(page, NR_WRITEBACK); > } I didn't find that chunk, perhaps it's lost due to rebase.. > There isn't a unified interface to dec/inc writeback accounting, so > I just follow that. > Maybe we can rework account_page_writeback() to also account > dec in? The current seperate inc/dec paths are fine. It sounds like over-engineering if going any further. I'm a bit worried about some 3rd party kernel module to call account_page_writeback() without mem_cgroup_begin/end_update_page_stat(). Will that lead to serious locking issues, or merely inaccurate accounting? Thanks, Fengguang