From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx181.postini.com [74.125.245.181]) by kanga.kvack.org (Postfix) with SMTP id 74A076B0002 for ; Wed, 13 Mar 2013 05:59:30 -0400 (EDT) Received: by mail-bk0-f50.google.com with SMTP id jg9so345703bkc.37 for ; Wed, 13 Mar 2013 02:59:28 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <514043B5.1090205@jp.fujitsu.com> References: <1362489058-3455-1-git-send-email-glommer@parallels.com> <1362489058-3455-3-git-send-email-glommer@parallels.com> <51368D80.20701@jp.fujitsu.com> <5136FEC2.2050004@parallels.com> <51371E4A.7090807@jp.fujitsu.com> <51371FEF.3020507@parallels.com> <513721A5.6080401@jp.fujitsu.com> <514043B5.1090205@jp.fujitsu.com> Date: Wed, 13 Mar 2013 17:59:28 +0800 Message-ID: Subject: Re: [PATCH v2 2/5] memcg: provide root figures from system totals From: Sha Zhengju Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Kamezawa Hiroyuki Cc: Glauber Costa , linux-mm@kvack.org, cgroups@vger.kernel.org, Tejun Heo , Andrew Morton , Michal Hocko , anton.vorontsov@linaro.org, Johannes Weiner , Mel Gorman On Wed, Mar 13, 2013 at 5:15 PM, Kamezawa Hiroyuki wrote: > (2013/03/13 15:58), Sha Zhengju wrote: >> >> On Wed, Mar 6, 2013 at 6:59 PM, Kamezawa Hiroyuki >> wrote: >>> >>> (2013/03/06 19:52), Glauber Costa wrote: >>>> >>>> On 03/06/2013 02:45 PM, Kamezawa Hiroyuki wrote: >>>>> >>>>> (2013/03/06 17:30), Glauber Costa wrote: >>>>>> >>>>>> On 03/06/2013 04:27 AM, Kamezawa Hiroyuki wrote: >>>>>>> >>>>>>> (2013/03/05 22:10), Glauber Costa wrote: >>>>>>>> >>>>>>>> + case _MEMSWAP: { >>>>>>>> + struct sysinfo i; >>>>>>>> + si_swapinfo(&i); >>>>>>>> + >>>>>>>> + return ((memcg_read_root_rss() + >>>>>>>> + atomic_long_read(&vm_stat[NR_FILE_PAGES])) << PAGE_SHIFT) >>>>>>>> + >>>>>>>> + i.totalswap - i.freeswap; >>>>>>> >>>>>>> >>>>>>> How swapcache is handled ? ...and How kmem works with this calc ? >>>>>>> >>>>>> I am ignoring kmem, because we don't account kmem for the root cgroup >>>>>> anyway. >>>>>> >>>>>> Setting the limit is invalid, and we don't account until the limit is >>>>>> set. Then it will be 0, always. >>>>>> >>>>>> For swapcache, I am hoping that totalswap - freeswap will cover >>>>>> everything swap related. If you think I am wrong, please enlighten me. >>>>>> >>>>> >>>>> i.totalswap - i.freeswap = # of used swap entries. >>>>> >>>>> SwapCache can be rss and used swap entry at the same time. >>>>> >>>> >>>> Well, yes, but the rss entries would be accounted for in get_mm_rss(), >>>> won't they ? >>>> >>>> What am I missing ? >>> >>> >>> >>> I think the correct caluculation is >>> >>> Sum of all RSS + All file caches + (i.total_swap - i.freeswap - # of >>> mapped SwapCache) >>> >>> >>> In the patch, mapped SwapCache is counted as both of rss and swap. >>> >> >> After a quick look, swapcache is counted as file pages and meanwhile >> use a swap entry at the same time(__add_to{delete_from}_swap_cache()). >> Even though, I think we still do not need to exclude swapcache out, >> because it indeed uses two copy of resource: one is swap entry, one is >> cache, so the usage should count both of them in. >> >> What I think it matters is that swapcache may be counted as both file >> pages and rss(if it's a process's anonymous page), which we need to >> subtract # of swapcache to avoid double-counting. But it isn't always >> so: a shmem/tmpfs page may use swapcache and be counted as file pages >> but not a rss, then we can not subtract swapcache... Is there anything >> I lost? >> > > > Please don't think difficult. All pages for user/caches are counted in > LRU. All swap-entry usage can be cauht by total_swap_pages - nr_swap_pages. > We just need to subtract number of swap-cache which is double counted > as swap-entry and a page in LRU. > > NR_ACTIVE_ANON + NR_INACTIVE_ANON + NR_ACTIVE_FILE + NR_INACTIVE_FILE > + NR_UNEVICTABLE + total_swap_pages - nr_swap_pages - NR_SWAP_CACHE > Using LRU numbers is more suitable. But forgive me, I still doubt whether we should subtract NR_SWAP_CACHE out because it uses both a swap entry and a page cache and it isn't a real double counting. Thanks, Sha -- 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