From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12FA5C433DF for ; Tue, 13 Oct 2020 14:44:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7EC9E2488C for ; Tue, 13 Oct 2020 14:44:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="R0rBuENa" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730361AbgJMOog (ORCPT ); Tue, 13 Oct 2020 10:44:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38358 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728495AbgJMOog (ORCPT ); Tue, 13 Oct 2020 10:44:36 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 06A6BC0613D0; Tue, 13 Oct 2020 07:44:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=Content-Transfer-Encoding:Content-Type: In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To:Subject:Sender :Reply-To:Content-ID:Content-Description; bh=gKRE5e5JfpskUWXmYMgE/etrXSbKNWpPiTlTnQ/1/ws=; b=R0rBuENacNrEsc1Bdj2P9Tk79p QQX4a1UYYI0zagRHF/Vz1dpEwOhrRrNLQyDN+LcRY8fHQZ/+ax5c/c1pEK3uVi0IOR0GWbr+SLsqs nxsSI+xrio4qTmdQ/2PrywhF3xqIvfl1AmXrgGijj7/QChZ+UD7kkAvbSJF3c+1ChWRn4P2M03bgz 4oiTsAKgm/bG2XdBJZcFXYPjyF3nN/1y2XgcBfYbInHolOpjDY49FThLQg2loIxiinaPU518L8EYs wNXoXr6IiYfGJ4UrRsCihWloD1uIIJNneCgVhy3lJKxJhK6pLc0Na/uxOVrwhg6bVHPCCp9ExRCvx v9OFBAjg==; Received: from [2601:1c0:6280:3f0::507c] by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kSLXE-0006p7-QB; Tue, 13 Oct 2020 14:44:17 +0000 Subject: Re: [External] Re: [PATCH] mm: proc: add Sock to /proc/meminfo To: Mike Rapoport , Muchun Song Cc: Eric Dumazet , Eric Dumazet , Cong Wang , Greg KH , rafael@kernel.org, "Michael S. Tsirkin" , Jason Wang , David Miller , Jakub Kicinski , Alexey Dobriyan , Andrew Morton , Alexey Kuznetsov , Hideaki YOSHIFUJI , Steffen Klassert , Herbert Xu , Shakeel Butt , Will Deacon , Michal Hocko , Roman Gushchin , Neil Brown , Sami Tolvanen , "Kirill A. Shutemov" , Feng Tang , Paolo Abeni , Willem de Bruijn , Florian Westphal , gustavoars@kernel.org, Pablo Neira Ayuso , Dexuan Cui , Jakub Sitnicki , Peter Zijlstra , Christian Brauner , "Eric W. Biederman" , Thomas Gleixner , dave@stgolabs.net, Michel Lespinasse , Jann Horn , chenqiwu@xiaomi.com, christophe.leroy@c-s.fr, Minchan Kim , Martin KaFai Lau , Alexei Starovoitov , Daniel Borkmann , Miaohe Lin , Kees Cook , LKML , virtualization@lists.linux-foundation.org, Linux Kernel Network Developers , linux-fsdevel , linux-mm , Michael Kerrisk References: <20201010103854.66746-1-songmuchun@bytedance.com> <9262ea44-fc3a-0b30-54dd-526e16df85d1@gmail.com> <20201013080906.GD4251@kernel.org> From: Randy Dunlap Message-ID: Date: Tue, 13 Oct 2020 07:43:59 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20201013080906.GD4251@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 10/13/20 1:09 AM, Mike Rapoport wrote: > On Mon, Oct 12, 2020 at 05:53:01PM +0800, Muchun Song wrote: >> On Mon, Oct 12, 2020 at 5:24 PM Eric Dumazet wrote: >>> >>> On 10/12/20 10:39 AM, Muchun Song wrote: >>>> On Mon, Oct 12, 2020 at 3:42 PM Eric Dumazet wrote: >>>>> >>>>> On Mon, Oct 12, 2020 at 6:22 AM Muchun Song wrote: >>>>>> >>>>>> On Mon, Oct 12, 2020 at 2:39 AM Cong Wang wrote: >>>>>>> >>>>>>> On Sat, Oct 10, 2020 at 3:39 AM Muchun Song wrote: >>>>>>>> >>>>>>>> The amount of memory allocated to sockets buffer can become significant. >>>>>>>> However, we do not display the amount of memory consumed by sockets >>>>>>>> buffer. In this case, knowing where the memory is consumed by the kernel >>>>>>> >>>>>>> We do it via `ss -m`. Is it not sufficient? And if not, why not adding it there >>>>>>> rather than /proc/meminfo? >>>>>> >>>>>> If the system has little free memory, we can know where the memory is via >>>>>> /proc/meminfo. If a lot of memory is consumed by socket buffer, we cannot >>>>>> know it when the Sock is not shown in the /proc/meminfo. If the unaware user >>>>>> can't think of the socket buffer, naturally they will not `ss -m`. The >>>>>> end result >>>>>> is that we still don’t know where the memory is consumed. And we add the >>>>>> Sock to the /proc/meminfo just like the memcg does('sock' item in the cgroup >>>>>> v2 memory.stat). So I think that adding to /proc/meminfo is sufficient. >>>>>> >>>>>>> >>>>>>>> static inline void __skb_frag_unref(skb_frag_t *frag) >>>>>>>> { >>>>>>>> - put_page(skb_frag_page(frag)); >>>>>>>> + struct page *page = skb_frag_page(frag); >>>>>>>> + >>>>>>>> + if (put_page_testzero(page)) { >>>>>>>> + dec_sock_node_page_state(page); >>>>>>>> + __put_page(page); >>>>>>>> + } >>>>>>>> } >>>>>>> >>>>>>> You mix socket page frag with skb frag at least, not sure this is exactly >>>>>>> what you want, because clearly skb page frags are frequently used >>>>>>> by network drivers rather than sockets. >>>>>>> >>>>>>> Also, which one matches this dec_sock_node_page_state()? Clearly >>>>>>> not skb_fill_page_desc() or __skb_frag_ref(). >>>>>> >>>>>> Yeah, we call inc_sock_node_page_state() in the skb_page_frag_refill(). >>>>>> So if someone gets the page returned by skb_page_frag_refill(), it must >>>>>> put the page via __skb_frag_unref()/skb_frag_unref(). We use PG_private >>>>>> to indicate that we need to dec the node page state when the refcount of >>>>>> page reaches zero. >>>>>> >>>>> >>>>> Pages can be transferred from pipe to socket, socket to pipe (splice() >>>>> and zerocopy friends...) >>>>> >>>>> If you want to track TCP memory allocations, you always can look at >>>>> /proc/net/sockstat, >>>>> without adding yet another expensive memory accounting. >>>> >>>> The 'mem' item in the /proc/net/sockstat does not represent real >>>> memory usage. This is just the total amount of charged memory. >>>> >>>> For example, if a task sends a 10-byte message, it only charges one >>>> page to memcg. But the system may allocate 8 pages. Therefore, it >>>> does not truly reflect the memory allocated by the above memory >>>> allocation path. We can see the difference via the following message. >>>> >>>> cat /proc/net/sockstat >>>> sockets: used 698 >>>> TCP: inuse 70 orphan 0 tw 617 alloc 134 mem 13 >>>> UDP: inuse 90 mem 4 >>>> UDPLITE: inuse 0 >>>> RAW: inuse 1 >>>> FRAG: inuse 0 memory 0 >>>> >>>> cat /proc/meminfo | grep Sock >>>> Sock: 13664 kB >>>> >>>> The /proc/net/sockstat only shows us that there are 17*4 kB TCP >>>> memory allocations. But apply this patch, we can see that we truly >>>> allocate 13664 kB(May be greater than this value because of per-cpu >>>> stat cache). Of course the load of the example here is not high. In >>>> some high load cases, I believe the difference here will be even >>>> greater. >>>> >>> >>> This is great, but you have not addressed my feedback. >>> >>> TCP memory allocations are bounded by /proc/sys/net/ipv4/tcp_mem >>> >>> Fact that the memory is forward allocated or not is a detail. >>> >>> If you think we must pre-allocate memory, instead of forward allocations, >>> your patch does not address this. Adding one line per consumer in /proc/meminfo looks >>> wrong to me. >> >> I think that the consumer which consumes a lot of memory should be added >> to the /proc/meminfo. This can help us know the user of large memory. >> >>> >>> If you do not want 9.37 % of physical memory being possibly used by TCP, >>> just change /proc/sys/net/ipv4/tcp_mem accordingly ? >> >> We are not complaining about TCP using too much memory, but how do >> we know that TCP uses a lot of memory. When I firstly face this problem, >> I do not know who uses the 25GB memory and it is not shown in the /proc/meminfo. >> If we can know the amount memory of the socket buffer via /proc/meminfo, we >> may not need to spend a lot of time troubleshooting this problem. Not everyone >> knows that a lot of memory may be used here. But I believe many people >> should know /proc/meminfo to confirm memory users. > > If I undestand correctly, the problem you are trying to solve is to > simplify troubleshooting of memory usage for people who may not be aware > that networking stack can be a large memory consumer. > > For that a paragraph in 'man 5 proc' maybe a good start: > >>>From ddbcf38576d1a2b0e36fe25a27350d566759b664 Mon Sep 17 00:00:00 2001 > From: Mike Rapoport > Date: Tue, 13 Oct 2020 11:07:35 +0300 > Subject: [PATCH] proc.5: meminfo: add not anout network stack memory > consumption > > Signed-off-by: Mike Rapoport > --- > man5/proc.5 | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/man5/proc.5 b/man5/proc.5 > index ed309380b..8414676f1 100644 > --- a/man5/proc.5 > +++ b/man5/proc.5 > @@ -3478,6 +3478,14 @@ Except as noted below, > all of the fields have been present since at least Linux 2.6.0. > Some fields are displayed only if the kernel was configured > with various options; those dependencies are noted in the list. > +.IP > +Note that significant part of memory allocated by the network stack > +is not accounted in the file. > +The memory consumption of the network stack can be queried > +using > +.IR /proc/net/sockstat > +or > +.BR ss (8) > .RS > .TP > .IR MemTotal " %lu" Hi Mike, Could you tell us what units those values are in? or is that already explained somewhere else? thanks. -- ~Randy