Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756632Ab1CGXrb (ORCPT ); Mon, 7 Mar 2011 18:47:31 -0500 Received: from smtp-out.google.com ([216.239.44.51]:42258 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754063Ab1CGXr3 (ORCPT ); Mon, 7 Mar 2011 18:47:29 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=google.com; s=beta; h=date:from:x-x-sender:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version:content-type; b=I/0MQCfmty0Q/5GHfC/bekvbZuzmzMQ6x9xXeHFqhiY+2L+qN4ofWjiLBErEigFWi2 3v9Vfm3qzIsBvHxgEWtg== Date: Mon, 7 Mar 2011 15:47:23 -0800 (PST) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Andrew Morton cc: Naoya Horiguchi , Dave Hansen , Petr Holasek , linux-kernel@vger.kernel.org, emunson@mgebm.net, anton@redhat.com, Andi Kleen , Mel Gorman , Wu Fengguang , Nishanth Aravamudan , linux-mm@kvack.org Subject: Re: [PATCH] hugetlb: /proc/meminfo shows data for all sizes of hugepages In-Reply-To: <20110307152516.fee931bb.akpm@linux-foundation.org> Message-ID: References: <1299503155-6210-1-git-send-email-pholasek@redhat.com> <1299527214.8493.13263.camel@nimitz> <20110307145149.97e6676e.akpm@linux-foundation.org> <20110307231448.GA2946@spritzera.linux.bs1.fc.nec.co.jp> <20110307152516.fee931bb.akpm@linux-foundation.org> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3891 Lines: 96 On Mon, 7 Mar 2011, Andrew Morton wrote: > > > > On Mon, 2011-03-07 at 14:05 +0100, Petr Holasek wrote: > > > > > + for_each_hstate(h) > > > > > + 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)); > > > > > } > > > > > > > > It sounds like now we'll get a meminfo that looks like: > > > > > > > > ... > > > > AnonHugePages: 491520 kB > > > > HugePages_Total: 5 > > > > HugePages_Free: 2 > > > > HugePages_Rsvd: 3 > > > > HugePages_Surp: 1 > > > > Hugepagesize: 2048 kB > > > > HugePages_Total: 2 > > > > HugePages_Free: 1 > > > > HugePages_Rsvd: 1 > > > > HugePages_Surp: 1 > > > > Hugepagesize: 1048576 kB > > > > DirectMap4k: 12160 kB > > > > DirectMap2M: 2082816 kB > > > > DirectMap1G: 2097152 kB > > > > > > > > At best, that's a bit confusing. There aren't any other entries in > > > > meminfo that occur more than once. Plus, this information is available > > > > in the sysfs interface. Why isn't that sufficient? > > > > > > > > Could we do something where we keep the default hpage_size looking like > > > > it does now, but append the size explicitly for the new entries? > > > > > > > > HugePages_Total(1G): 2 > > > > HugePages_Free(1G): 1 > > > > HugePages_Rsvd(1G): 1 > > > > HugePages_Surp(1G): 1 > > > > > > > > > > Let's not change the existing interface, please. > > > > > > Adding new fields: OK. > > > Changing the way in whcih existing fields are calculated: OKish. > > > Renaming existing fields: not OK. > > > > How about lining up multiple values in each field like this? > > > > HugePages_Total: 5 2 > > HugePages_Free: 2 1 > > HugePages_Rsvd: 3 1 > > HugePages_Surp: 1 1 > > Hugepagesize: 2048 1048576 kB > > ... > > > > This doesn't change the field names and the impact for user space > > is still small? > > It might break some existing parsers, dunno. > > It was a mistake to assume that all hugepages will have the same size > for all time, and we just have to live with that mistake. > I'm not sure it was a mistake: the kernel has a default hugepage size and that's what the global /proc/sys/vm/nr_hugepages tunable uses, so it seems appropriate that its statistics are exported in the global /proc/meminfo. > I'd suggest that we leave meminfo alone, just ensuring that its output > makes some sense. Instead create a new interface which presents all > the required info in a sensible fashion and migrate usersapce reporting > tools over to that interface. Just let the meminfo field die a slow > death. > (Adding Nishanth to the cc) It's already there, all this data is available for all the configured hugepage sizes via /sys/kernel/mm/hugepages/hugepages-kB/ as described by Documentation/ABI/testing/sysfs-kernel-mm-hugepages. It looks like Nishanth and others put quite a bit of effort into making as stable of an API as possible for this information. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/