From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f200.google.com (mail-wr0-f200.google.com [209.85.128.200]) by kanga.kvack.org (Postfix) with ESMTP id DA0136B0069 for ; Tue, 21 Nov 2017 14:19:11 -0500 (EST) Received: by mail-wr0-f200.google.com with SMTP id y41so8488884wrc.22 for ; Tue, 21 Nov 2017 11:19:11 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id u21si11298218wrc.235.2017.11.21.11.19.10 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 21 Nov 2017 11:19:10 -0800 (PST) Date: Tue, 21 Nov 2017 11:19:07 -0800 From: Andrew Morton Subject: Re: [PATCH v2] mm: show total hugetlb memory consumption in /proc/meminfo Message-Id: <20171121111907.6952d50adcbe435b1b6b4576@linux-foundation.org> In-Reply-To: <20171121151545.GA23974@castle> References: <20171115231409.12131-1-guro@fb.com> <20171120165110.587918bf75ffecb8144da66c@linux-foundation.org> <20171121151545.GA23974@castle> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Roman Gushchin 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 Tue, 21 Nov 2017 15:15:55 +0000 Roman Gushchin wrote: > > > + > > > + 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. > OK, I misread the handling of `count' -> HugePages_Total. It seems unnecessarily obscure? for_each_hstate(h) { unsigned long count = h->nr_huge_pages; total += (PAGE_SIZE << huge_page_order(h)) * count; if (h == &default_hstate) seq_printf(m, "HugePages_Total: %5lu\n" "HugePages_Free: %5lu\n" "HugePages_Rsvd: %5lu\n" "HugePages_Surp: %5lu\n" "Hugepagesize: %8lu kB\n", count, h->free_huge_pages, h->resv_huge_pages, h->surplus_huge_pages, (PAGE_SIZE << huge_page_order(h)) / 1024); } seq_printf(m, "Hugetlb: %8lu kB\n", total / 1024); Why not 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) total += (PAGE_SIZE << huge_page_order(h)) * h->nr_huge_pages; seq_printf(m, "Hugetlb: %8lu kB\n", total / 1024); ? -- 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