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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 72A63C433EF for ; Thu, 6 Jan 2022 03:35:38 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 99B166B0078; Wed, 5 Jan 2022 22:35:37 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 94B3B6B007B; Wed, 5 Jan 2022 22:35:37 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 812FD6B007E; Wed, 5 Jan 2022 22:35:37 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0160.hostedemail.com [216.40.44.160]) by kanga.kvack.org (Postfix) with ESMTP id 728FF6B0078 for ; Wed, 5 Jan 2022 22:35:37 -0500 (EST) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 2C1DF8229B42 for ; Thu, 6 Jan 2022 03:35:37 +0000 (UTC) X-FDA: 78998447514.16.97F6EE3 Received: from mail-yb1-f176.google.com (mail-yb1-f176.google.com [209.85.219.176]) by imf13.hostedemail.com (Postfix) with ESMTP id 046CE20006 for ; Thu, 6 Jan 2022 03:35:16 +0000 (UTC) Received: by mail-yb1-f176.google.com with SMTP id d1so3694177ybh.6 for ; Wed, 05 Jan 2022 19:35:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=VhCtBh9G+9Rq3UzhrUmX4qOWZGDQBagUdx1KxmXNCUU=; b=Unx7MsOTF3iBIkzcDjUGc/Hwk1xF3imXeLxXvHDk3YAGS/3Q1gvF0MmE2Gz+qlqSKf UimyQLdx13fXmvEnS7nvvLDfUXqbqkKPQuyb/StgtYIogr5z2y37q7eN3BK68GOoP7D0 BQTDY1+UtpFGDwOWQ2Y79VEfk1Po8m3bCB6Qq0RSduk0Bpn4kk0uYvPEpfYe/FMbW+oQ yKI14c1UJXhWmMFMLGm/yldfRNvJD3aJaYaDonTthjth8433U+wEco2cmgNjPb1lLk+D FU0xnMSpGtIqeZZ2VJbilITNZvItjLMKlMIpid+Xvf+25diKXAEYiFKMoBym3Iwqhcta iCdw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=VhCtBh9G+9Rq3UzhrUmX4qOWZGDQBagUdx1KxmXNCUU=; b=qAj38wGavAhQpXyiyeplNTUPjgWzI1MIjVz8E2gACeWaR4SrEXfsUd+w+9EoCXAzvC Of7f3uvfuoOGA/SR4L/mT+Y7XGtIfKr3CuKGkJHZNffCPDb05ORxUI9pK2l9cibVfxC2 mdVPomRCjxyJ8zlxkTKC7Fq5mFcdGtxO2VnhWNf7T4I1euNkuy56mcckFlgIgnZ2Lypc 86jTnpIdDJH+YH4nX8rM3vuI6ST7VOMAyuo1U87DIsbvvhIB0seeyzhR2xIiFsquQn1R Mt35ksDSo3SHOm7/xKhfJUTPMGgsUj9MfY6r7TTy4u+qNN+0dpIiZxojysgSnbn1PsSo nLiw== X-Gm-Message-State: AOAM530I0irVjbcnlGca3cSl3JkO/PF/v5dsRk4oFS50ANvvHLi2XnkE OH2BFCo8IQKa89tPgBiuHZxDsldhIVUyR7Wl/MyRJg== X-Google-Smtp-Source: ABdhPJxLB871qfyaC0YcbeoW0XO6II0Pr+i3wgfkb5I1MNAgQRDDpwl/ZkNrhj0iJGor2gwCYyskjboIbezk1yYDgxI= X-Received: by 2002:a25:3890:: with SMTP id f138mr63404636yba.703.1641440134052; Wed, 05 Jan 2022 19:35:34 -0800 (PST) MIME-Version: 1.0 References: <20211220085649.8196-1-songmuchun@bytedance.com> <20211220085649.8196-14-songmuchun@bytedance.com> <20220105170348.GA21070@blackbody.suse.cz> In-Reply-To: <20220105170348.GA21070@blackbody.suse.cz> From: Muchun Song Date: Thu, 6 Jan 2022 11:34:58 +0800 Message-ID: Subject: Re: [PATCH v5 13/16] mm: memcontrol: reuse memory cgroup ID for kmem ID To: =?UTF-8?Q?Michal_Koutn=C3=BD?= , =?UTF-8?Q?Mika_Penttil=C3=A4?= Cc: Matthew Wilcox , Andrew Morton , Johannes Weiner , Michal Hocko , Vladimir Davydov , Shakeel Butt , Roman Gushchin , Yang Shi , Alex Shi , Wei Yang , Dave Chinner , trond.myklebust@hammerspace.com, anna.schumaker@netapp.com, jaegeuk@kernel.org, chao@kernel.org, Kari Argillander , linux-fsdevel , LKML , Linux Memory Management List , linux-nfs@vger.kernel.org, Qi Zheng , Xiongchun duan , Fam Zheng , Muchun Song Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: fg6zj9pjfrtb3qstw5t5rsq5e9eiw4zb X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 046CE20006 Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=bytedance-com.20210112.gappssmtp.com header.s=20210112 header.b=Unx7MsOT; spf=pass (imf13.hostedemail.com: domain of songmuchun@bytedance.com designates 209.85.219.176 as permitted sender) smtp.mailfrom=songmuchun@bytedance.com; dmarc=pass (policy=none) header.from=bytedance.com X-HE-Tag: 1641440116-544389 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Jan 6, 2022 at 1:03 AM Michal Koutn=C3=BD wrote: > > On Mon, Dec 20, 2021 at 04:56:46PM +0800, Muchun Song wrote: > > There are two idrs being used by memory cgroup, one is for kmem ID, > > another is for memory cgroup ID. The maximum ID of both is 64Ki. > > Both of them can limit the total number of memory cgroups. > > Actually, we can reuse memory cgroup ID for kmem ID to simplify the > > code. > > An interesting improvement. > > I'm a bit dense -- what's the purpose the MEM_CGROUP_ID_DIFF offset? Hi Michal and Mika, MEM_CGROUP_ID_DIFF is introduced to be consistent with before that kmem ID starts with -1 and has no holes. Actually, it can be dropped and make memcg->kmemcg_id equal to memcg->id.id directly. > Couldn't this deduplication be extended to only use mem_cgroup.id.id > instead of mem_cgroup.kmemcg_id? (With a boolean telling whether kmem > accounting is active.) > Not easy to completely remove memcg->kmemcg_id since this filed will be used to sync list_lru reparenting which will change memcg->kmemcg_id to its parent's kmem ID (more details refers to memcg_drain_all_list_lrus() in patch 10 of this series). Thanks.