From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx123.postini.com [74.125.245.123]) by kanga.kvack.org (Postfix) with SMTP id C69B46B004D for ; Thu, 14 Mar 2013 06:16:07 -0400 (EDT) Received: from /spool/local by e28smtp03.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 14 Mar 2013 15:43:01 +0530 Received: from d28relay02.in.ibm.com (d28relay02.in.ibm.com [9.184.220.59]) by d28dlp01.in.ibm.com (Postfix) with ESMTP id 0B71DE004E for ; Thu, 14 Mar 2013 15:47:23 +0530 (IST) Received: from d28av03.in.ibm.com (d28av03.in.ibm.com [9.184.220.65]) by d28relay02.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r2EAFwhT21233896 for ; Thu, 14 Mar 2013 15:45:58 +0530 Received: from d28av03.in.ibm.com (loopback [127.0.0.1]) by d28av03.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r2EAG08h011511 for ; Thu, 14 Mar 2013 21:16:00 +1100 Date: Thu, 14 Mar 2013 18:15:58 +0800 From: Wanpeng Li Subject: Re: [PATCH] mm/hugetlb: fix total hugetlbfs pages count when memory overcommit accouting Message-ID: <20130314101558.GA19776@hacker.(null)> Reply-To: Wanpeng Li References: <1363158511-21272-1-git-send-email-liwanp@linux.vnet.ibm.com> <20130314094419.GA11631@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130314094419.GA11631@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Andrew Morton , "Aneesh Kumar K.V" , Hillf Danton , KAMEZAWA Hiroyuki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Wanpeng Li On Thu, Mar 14, 2013 at 10:44:19AM +0100, Michal Hocko wrote: >On Wed 13-03-13 15:08:31, Wanpeng Li wrote: >> After commit 42d7395f ("mm: support more pagesizes for MAP_HUGETLB/SHM_HUGETLB") >> be merged, kernel permit multiple huge page sizes, > Hi Michal, >multiple huge page sizes were possible long before this commit. The >above mentioned patch just made their usage via IPC much easier. You >could do the same previously (since a137e1cc) by mounting hugetlbfs with >a specific page size as a parameter and using mmap. > Agreed. >> and when the system administrator has configured the system to provide >> huge page pools of different sizes, application can choose the page >> size used for their allocation. > >> However, just default size of huge page pool is statistical when >> memory overcommit accouting, the bad is that this will result in >> innocent processes be killed by oom-killer later. > >Why would an innnocent process be killed? The overcommit calculation >is incorrect, that is true, but this just means that an unexpected >ENOMEM/EFAULT or SIGSEGV would be returned, no? How an OOM could be a >result? Agreed. > >> Fix it by statistic all huge page pools of different sizes provided by >> administrator. > >The patch makes sense but the description is misleading AFAICS. > Thanks for your pointing out Michal, I will update the description. :-) Regards, Wanpeng Li >> Testcase: >> boot: hugepagesz=1G hugepages=1 >> before patch: >> egrep 'CommitLimit' /proc/meminfo >> CommitLimit: 55434168 kB >> after patch: >> egrep 'CommitLimit' /proc/meminfo >> CommitLimit: 54909880 kB >> >> Signed-off-by: Wanpeng Li >> --- >> mm/hugetlb.c | 7 +++++-- >> 1 file changed, 5 insertions(+), 2 deletions(-) >> >> diff --git a/mm/hugetlb.c b/mm/hugetlb.c >> index cdb64e4..9e25040 100644 >> --- a/mm/hugetlb.c >> +++ b/mm/hugetlb.c >> @@ -2124,8 +2124,11 @@ int hugetlb_report_node_meminfo(int nid, char *buf) >> /* Return the number pages of memory we physically have, in PAGE_SIZE units. */ >> unsigned long hugetlb_total_pages(void) >> { >> - struct hstate *h = &default_hstate; >> - return h->nr_huge_pages * pages_per_huge_page(h); >> + struct hstate *h; >> + unsigned long nr_total_pages = 0; >> + for_each_hstate(h) >> + nr_total_pages += h->nr_huge_pages * pages_per_huge_page(h); >> + return nr_total_pages; >> } >> >> static int hugetlb_acct_memory(struct hstate *h, long delta) >> -- >> 1.7.11.7 >> >> -- >> 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 > >-- >Michal Hocko >SUSE Labs -- 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