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 750C3C27C4F for ; Fri, 21 Jun 2024 21:37:59 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D48A78D01A8; Fri, 21 Jun 2024 17:37:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CF8C08D01A5; Fri, 21 Jun 2024 17:37:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BC0AA8D01A8; Fri, 21 Jun 2024 17:37:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 9BD058D01A5 for ; Fri, 21 Jun 2024 17:37:58 -0400 (EDT) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 437AF1611CC for ; Fri, 21 Jun 2024 21:37:58 +0000 (UTC) X-FDA: 82256208636.20.3C511A8 Received: from mail-pl1-f177.google.com (mail-pl1-f177.google.com [209.85.214.177]) by imf25.hostedemail.com (Postfix) with ESMTP id 72D5FA0018 for ; Fri, 21 Jun 2024 21:37:56 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=URzhVopJ; spf=pass (imf25.hostedemail.com: domain of namhyung@google.com designates 209.85.214.177 as permitted sender) smtp.mailfrom=namhyung@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1719005870; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Tdl1OKQDbYesTFf97HHJ8ni2BcNi3xmwAH+G4Q6ZF6k=; b=b8THFsNA9GwvpRqogAmKgmFTSZvpduVcHQpYjQswASamp2YzqpzkcE7INmgC0DA5UoqMg7 3BkKn9v+vzPr5n9+zaewHcluAIwiW3Z42BcSmxupvYwOQ387jfJF7xGWO83p1C/BQGJ9kk zWcM5jzOZBZ7Oqu0YZ3pryeZtU9f5Vc= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=URzhVopJ; spf=pass (imf25.hostedemail.com: domain of namhyung@google.com designates 209.85.214.177 as permitted sender) smtp.mailfrom=namhyung@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1719005870; a=rsa-sha256; cv=none; b=JOpBABQqzHRlaeTrTOAc4ZVxai/dV6a1wr/pLLspJ5Cn21z34mpxajQjpeu3OPVvmtluvh 6X7Ib6r7ary3p+jvSnOinsgMH7LSJxSAr+FpzAbubfTCMFbAY+9J4pAxGbVZXyTr9HVp5A av27ukcaszBYfwU/MW28TytvmMT7pX8= Received: by mail-pl1-f177.google.com with SMTP id d9443c01a7336-1ee5f3123d8so243785ad.1 for ; Fri, 21 Jun 2024 14:37:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1719005875; x=1719610675; darn=kvack.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=Tdl1OKQDbYesTFf97HHJ8ni2BcNi3xmwAH+G4Q6ZF6k=; b=URzhVopJVDZYa3UT5bfDx7mYf00AQY5jh8eba3FUHx60RSLIKeMdRQBa2eY40ijs4x KgaLzvWlNPt+MF5BvxXcHHJV5PljNmvdIq029hkYwimWv4tIXPMcCPTmnpMDwxu9LuHq Xyf22AN/EcbmhGbtT8UKar2gv+VdRn7CgClcft8eSUjts0Ph+LzAzCfA4Q1ZETbPiFC5 HvPjxiTOBpeayPf3R+Rq4OJGle3ddKNgmCOl3d/oM/pR0G4hr36XKxi5n1nXBmMzb9yv DjcPhMxHB+0bi7NMY7V5ZtCc0BQM0mQKq0pomGH5xtmBgZmQXbXzMPDwwWKF6NI0KPPL krWg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1719005875; x=1719610675; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=Tdl1OKQDbYesTFf97HHJ8ni2BcNi3xmwAH+G4Q6ZF6k=; b=LHoH1ADJ1Lce7r+U3oIYoSEDlPOyn82OmNHa5tqLyLOOWzgsyuHdGxYlAxMPSFvx67 jEH67mraATyAlJbLb3bnSwFGa0iBKWbjgNrKkKCqzRhMz/pcLK+WrBu1pC2PLJveMRpo zlUzD3QoPzCvu6NRLXHew76frhr+qDadYFYEhtAwQpXK0Qpnd5GgaZv21xzXkYtm+fWr PaWlcTH5PUCqrD4b/aukfhfdvbB/IinpEOAujTF83+Pc3qu+yJEvhWQf58/70gmBHz4n k2aml4T6hXq11ETvmq/atAyeV6uTZkmbaANmbL5NJ9kWwPo0o/TYaguTUinKRapyfgzO pvCQ== X-Forwarded-Encrypted: i=1; AJvYcCUruAcl5mIjLdrr5BSXc0e7L6c0VjvSnubuOg6WAqr7DZ4l/DBRjtploETjNK978Ve0drxQ+boJ1et99mz46KpG3hU= X-Gm-Message-State: AOJu0YzLvKBcpkE4fNJPf/LNzGzdCmMqkFmrIvKX1ukmK9Uwqr7MmDRl YOhl9dhx/nk3m1hOS5fxYl19hvTWf4stNem/+xdEX/DIXfLIjlTdI4VFLfmLCJxy2l7NQCZWoJj j2bPyIig/JgbK4aCwJr1KuXvLlQfxh0CrsD3M X-Google-Smtp-Source: AGHT+IGaMF2nPa85fv2jlDUdwN2h3WHfBYUB76bl2JqpDMH7yG5frrKB3mu6m9eqVnbOHBnrSucyeOcbfmehYO3lqNs= X-Received: by 2002:a17:902:900a:b0:1f4:9480:652f with SMTP id d9443c01a7336-1fa09fee620mr482315ad.14.1719005874838; Fri, 21 Jun 2024 14:37:54 -0700 (PDT) MIME-Version: 1.0 References: <07e7d078-0c9d-6a1f-1ab5-295f86974b72@google.com> In-Reply-To: From: Namhyung Kim Date: Fri, 21 Jun 2024 14:37:43 -0700 Message-ID: Subject: Re: MM global locks as core counts quadruple To: Tejun Heo Cc: David Rientjes , Andrew Morton , "Liam R. Howlett" , Suren Baghdasaryan , Matthew Wilcox , Christoph Lameter , "Paul E. McKenney" , Johannes Weiner , Davidlohr Bueso , linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 72D5FA0018 X-Stat-Signature: ce355dzcfkrjwuts6rmwygdxof3fp7nb X-Rspam-User: X-HE-Tag: 1719005876-841658 X-HE-Meta: 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 kYkF52kR /Rh7x8FKjJGxL9qFcu9UFRzlns3GRip7M+WBOZ3TSEXJJHm4siDd6oFBtCHJQI0S0dAbya6IKxSeKKG0LsE+jKrZiwZKXQj1XgsxpLq0WsUgs/qXeK3YIW2gDnGcEfeD3eQ5Q2n1PvfC6ZMJsF3GzbvSFI2PnOPrXKq9qa3xCfAUUI2yupVf4ljUHdEyYZVhu7QnFH3XjZhZdheY4g2KX3LpxBH5zUN1FNHiB 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: List-Subscribe: List-Unsubscribe: Hello, On Fri, Jun 21, 2024 at 12:10=E2=80=AFPM Tejun Heo wrote: > > Hello, > > On Thu, Jun 20, 2024 at 05:35:45PM -0700, David Rientjes wrote: > > As core counts are rapidly expanding over the next four years, Namhyung > > and I were looking at global locks that we're already seeing high > > contention on even today. > > > > Some of these are not MM specific: > > - cgroup_mutex > > Our machines are getting bigger but we aren't creating and destroying > cgroups frequently enough for this to matter. But yeah, I can see how thi= s > can be a problem. > > > - cgroup_threadgroup_rwsem > > This one shouldn't matter at all in setups where new cgroups are populate= d > with CLONE_INTO_CGROUP and not migrated further. The lock isn't grabbed i= n > such usage pattern, which should be the vast majority already, I think. A= re > you guys migrating tasks a lot or not using CLONE_INTO_CGROUP? I'm afraid there are still some use cases in Google that migrate processes and/or threads between cgroups. :( Thanks, Namhyung