From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f69.google.com (mail-pg0-f69.google.com [74.125.83.69]) by kanga.kvack.org (Postfix) with ESMTP id B79146B0033 for ; Tue, 21 Nov 2017 10:16:24 -0500 (EST) Received: by mail-pg0-f69.google.com with SMTP id s11so13127417pgc.15 for ; Tue, 21 Nov 2017 07:16:24 -0800 (PST) Received: from mx0b-00082601.pphosted.com (mx0b-00082601.pphosted.com. [67.231.153.30]) by mx.google.com with ESMTPS id k13si9686737pfb.37.2017.11.21.07.16.22 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 21 Nov 2017 07:16:23 -0800 (PST) Date: Tue, 21 Nov 2017 15:15:55 +0000 From: Roman Gushchin Subject: Re: [PATCH v2] mm: show total hugetlb memory consumption in /proc/meminfo Message-ID: <20171121151545.GA23974@castle> References: <20171115231409.12131-1-guro@fb.com> <20171120165110.587918bf75ffecb8144da66c@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20171120165110.587918bf75ffecb8144da66c@linux-foundation.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-mm@kvack.org, Michal Hocko , Johannes Weiner , Mike Kravetz , "Aneesh Kumar K.V" , Andrea Arcangeli , Dave Hansen , David Rientjes , kernel-team@fb.com, linux-kernel@vger.kernel.org On Mon, Nov 20, 2017 at 04:51:10PM -0800, Andrew Morton wrote: > On Wed, 15 Nov 2017 23:14:09 +0000 Roman Gushchin wrote: > > > Currently we display some hugepage statistics (total, free, etc) > > in /proc/meminfo, but only for default hugepage size (e.g. 2Mb). > > > > If hugepages of different sizes are used (like 2Mb and 1Gb on x86-64), > > /proc/meminfo output can be confusing, as non-default sized hugepages > > are not reflected at all, and there are no signs that they are > > existing and consuming system memory. > > > > To solve this problem, let's display the total amount of memory, > > consumed by hugetlb pages of all sized (both free and used). > > Let's call it "Hugetlb", and display size in kB to match generic > > /proc/meminfo style. > > > > For example, (1024 2Mb pages and 2 1Gb pages are pre-allocated): > > $ cat /proc/meminfo > > MemTotal: 8168984 kB > > MemFree: 3789276 kB > > <...> > > CmaFree: 0 kB > > HugePages_Total: 1024 > > HugePages_Free: 1024 > > HugePages_Rsvd: 0 > > HugePages_Surp: 0 > > Hugepagesize: 2048 kB > > Hugetlb: 4194304 kB > > DirectMap4k: 32632 kB > > DirectMap2M: 4161536 kB > > DirectMap1G: 6291456 kB > > > > Also, this patch updates corresponding docs to reflect > > Hugetlb entry meaning and difference between Hugetlb and > > HugePages_Total * Hugepagesize. > > > > ... > > > > --- a/mm/hugetlb.c > > +++ b/mm/hugetlb.c > > @@ -2973,20 +2973,32 @@ int hugetlb_overcommit_handler(struct ctl_table *table, int write, > > > > void hugetlb_report_meminfo(struct seq_file *m) > > { > > - struct hstate *h = &default_hstate; > > + struct hstate *h; > > + unsigned long total = 0; > > + > > if (!hugepages_supported()) > > return; > > - seq_printf(m, > > - "HugePages_Total: %5lu\n" > > - "HugePages_Free: %5lu\n" > > - "HugePages_Rsvd: %5lu\n" > > - "HugePages_Surp: %5lu\n" > > - "Hugepagesize: %8lu kB\n", > > - h->nr_huge_pages, > > - h->free_huge_pages, > > - h->resv_huge_pages, > > - h->surplus_huge_pages, > > - 1UL << (huge_page_order(h) + PAGE_SHIFT - 10)); > > + > > + for_each_hstate(h) { > > + unsigned long count = h->nr_huge_pages; > > + > > + total += (PAGE_SIZE << huge_page_order(h)) * count; > > + > > + if (h == &default_hstate) > > I'm not understanding this test. Are we assuming that default_hstate > always refers to the highest-index hstate? If so why, and is that > valid? As Mike and Michal pointed, default_hstate is defined as #define default_hstate (hstates[default_hstate_idx]), where default_hstate_idx can be altered by a boot argument. We're iterating over all states to calculate total and also print some additional info for the default size. Having a single loop guarantees consistency of these numbers. Thanks! -- 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