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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 5E6CEC433DF for ; Mon, 12 Oct 2020 08:40:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F1EFF208FE for ; Mon, 12 Oct 2020 08:40:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=bytedance-com.20150623.gappssmtp.com header.i=@bytedance-com.20150623.gappssmtp.com header.b="vqGvXRZV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727637AbgJLIkG (ORCPT ); Mon, 12 Oct 2020 04:40:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41124 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727482AbgJLIkF (ORCPT ); Mon, 12 Oct 2020 04:40:05 -0400 Received: from mail-pg1-x541.google.com (mail-pg1-x541.google.com [IPv6:2607:f8b0:4864:20::541]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B5E83C0613D2 for ; Mon, 12 Oct 2020 01:40:05 -0700 (PDT) Received: by mail-pg1-x541.google.com with SMTP id y14so13553411pgf.12 for ; Mon, 12 Oct 2020 01:40:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=nTI2YVEwOfgh9p+oFG+z1qgnrhBmz+BUoqQKcix3EZ0=; b=vqGvXRZVq1jW4sgEi8S0/sHNxlcmL0ZqERj4Pwa/WZ/ql0G1AeXGVR3f0CADFyveGx yE4XNBUehdPzqu2tIoeidrSoNM+0p+0j7cD6/4C60mkXbuwx65n9284S00AVMuCMxpzo uqC2OXUTVpLHQgjMfUzNeNti7tYU4VRki29c2wScgRT6DVhDhxHhld/yLPfdsOhNpiIT HjAcfMVzJE3T9Kbg0UMlUJz+JCT5AHgArYOkj2SUDhQXJV/3KxaCC79zC7ZAP/nVi9uH jN9YsFuUeBuLNATPATZ0u25+bWi/vJ+VL/CNOz+ep9qFyHAmUYLN9mhb4C6/FxmKGN2v G5Dw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=nTI2YVEwOfgh9p+oFG+z1qgnrhBmz+BUoqQKcix3EZ0=; b=ikMpLlyyJQkhDdIQnSX3MFH0pO9Mm290Z7Rn1SumP9OA09LXw3XoQU4ntmZapPcRI6 A3iXWesLJHJclX++6A1m6ybGLSEF1W679Pr8gm7yP2Q0blSvZ42UoGAUKaWfSc5JdJZ+ 2Ay4FAW8NtdP/MC3b8huKbX0t5gw9I3WQh+EQdlkUbsigxRN1BF5WU9tpXLibiOov9Ao lsuzd5O6nMUftgT0c6f4JrrF/Hbr8pAGb/ZdDJup0+YUjVJDHRZfXLx5IJ2HF/bmN0tg Ua4bIMrSg1XSHshm+pcSRbLAlYxwZEiU5j18++OjX1/WMUOnGHP89CSSYhm2EZ/djDUA njjA== X-Gm-Message-State: AOAM533oxjAouYUBi3hmuEx+8br5c367aBjduOx0Xdbk5i0wiM62czF1 hP07ttmw9jdEkG5O6yJU1ZJcXRzMGSnclnrdCkfUVA== X-Google-Smtp-Source: ABdhPJzNls6dEzlTfEwkc2JEA15IrxS4rfGeYvT3I9xltofknhxcsIMWp8gAk9p3+kZn0WPzJWpnMpGcH9se0bk2XaE= X-Received: by 2002:a63:fd0a:: with SMTP id d10mr12237891pgh.273.1602492005028; Mon, 12 Oct 2020 01:40:05 -0700 (PDT) MIME-Version: 1.0 References: <20201010103854.66746-1-songmuchun@bytedance.com> In-Reply-To: From: Muchun Song Date: Mon, 12 Oct 2020 16:39:28 +0800 Message-ID: Subject: Re: [External] Re: [PATCH] mm: proc: add Sock to /proc/meminfo To: Eric Dumazet Cc: 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 , rppt@kernel.org, Sami Tolvanen , "Kirill A. Shutemov" , Feng Tang , Paolo Abeni , Willem de Bruijn , Randy Dunlap , 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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Oct 12, 2020 at 3:42 PM Eric Dumazet wrote: > > On Mon, Oct 12, 2020 at 6:22 AM Muchun Song wr= ote: > > > > On Mon, Oct 12, 2020 at 2:39 AM Cong Wang wr= ote: > > > > > > On Sat, Oct 10, 2020 at 3:39 AM Muchun Song wrote: > > > > > > > > The amount of memory allocated to sockets buffer can become signifi= cant. > > > > However, we do not display the amount of memory consumed by sockets > > > > buffer. In this case, knowing where the memory is consumed by the k= ernel > > > > > > We do it via `ss -m`. Is it not sufficient? And if not, why not addin= g it there > > > rather than /proc/meminfo? > > > > If the system has little free memory, we can know where the memory is v= ia > > /proc/meminfo. If a lot of memory is consumed by socket buffer, we cann= ot > > 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=E2=80=99t know where the memory is consumed. And w= e add the > > Sock to the /proc/meminfo just like the memcg does('sock' item in the c= group > > 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 =3D 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 exa= ctly > > > 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 o= f > > 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. --=20 Yours, Muchun