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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A026AC43334 for ; Mon, 25 Jul 2022 16:52:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235692AbiGYQwX (ORCPT ); Mon, 25 Jul 2022 12:52:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47714 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231622AbiGYQwV (ORCPT ); Mon, 25 Jul 2022 12:52:21 -0400 Received: from mail-qv1-xf30.google.com (mail-qv1-xf30.google.com [IPv6:2607:f8b0:4864:20::f30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6E5921D0DB for ; Mon, 25 Jul 2022 09:52:19 -0700 (PDT) Received: by mail-qv1-xf30.google.com with SMTP id i13so8834050qvo.3 for ; Mon, 25 Jul 2022 09:52:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20210112.gappssmtp.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=j0BaZSzqD5eIgwyip/HS4aDnwW9Jp806htc77k2W+9I=; b=YrRC8+DcvcJ+j3/daDEZUkXI7wwrYxc1PEjLb5WJCKV4hOP1uHTC/ifMwxGxMiDkfx /A82VqK1LTw9pVhvRXWQeyXrrPJ2ZvCuG5iWP7cY8NmWkKUfWofwwTglQWitP4sLRpre NB5VpzmQIT0yR8C+q/8SpRe6N4qEXuOmhz9/zyJDdIRw6IQfETk2K2RZNRdauaalnISk ecXU6u6eJyO8O/HQW59YX4MJEK3q8L7+iGwgT+B0Xfmvz2s9vSCXiUlMoZjDizM7CmZj Pva3rt58bJXcA2sOVprKVekCrokJioAdbUfKQmHTFPMiKttfucAsODDHed2z6c5VspUe 9oNA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=j0BaZSzqD5eIgwyip/HS4aDnwW9Jp806htc77k2W+9I=; b=JXo9lJWV3bLta2K2h8Fs6mkkHRfzFC+bqd7MU/QpthROF7uMZw8OLt07TJZ79AZlqB mdghoaTx7tMVONou8JqpEl4S0e0y4X182pHYqAFI6zR+M5U4iimr04bTKDWrX6IffyeH WEVDp+ViHZHNW1prVqxxwSPLC+5kynyCSB08IRM7kxT55jG+wgVQXb8FV+mx6EwASZYa B68we9FCI94ibFxCbXJ2PuJg8fz2vcfCkCKPa3kjr7tggVEHxk+GwGwCm+m+cELgW+gO wiwqI1zCVjAvwTFPFOzaNOx6uAtl9FgkcOAsJVpTCXnklVDUrWMrSWumwtSwUY/3Aptl sv6w== X-Gm-Message-State: AJIora/jH0/5b2z59qMJ83De1VCNCHhRRsMgtJLcMA9XHvRXVts0MsI0 Z3lKyE9A0ztX9DTdTInAp/26Hw== X-Google-Smtp-Source: AGRyM1uv3LFH6aM79vzCkplcfzTZ3m25YJ7ns1XG6o8aG/GGTPTrtN6PwrSDI9Hn7ptl4H/XTiIloQ== X-Received: by 2002:ad4:5de4:0:b0:474:2384:a0e9 with SMTP id jn4-20020ad45de4000000b004742384a0e9mr11516834qvb.79.1658767938522; Mon, 25 Jul 2022 09:52:18 -0700 (PDT) Received: from localhost ([2620:10d:c091:480::1:994f]) by smtp.gmail.com with ESMTPSA id u20-20020ac858d4000000b00304f3e320f2sm7915678qta.4.2022.07.25.09.52.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Jul 2022 09:52:18 -0700 (PDT) Date: Mon, 25 Jul 2022 12:52:17 -0400 From: Johannes Weiner To: Chengming Zhou Cc: surenb@google.com, mingo@redhat.com, peterz@infradead.org, tj@kernel.org, corbet@lwn.net, akpm@linux-foundation.org, rdunlap@infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, songmuchun@bytedance.com, cgroups@vger.kernel.org Subject: Re: [PATCH 8/9] sched/psi: add kernel cmdline parameter psi_inner_cgroup Message-ID: References: <20220721040439.2651-1-zhouchengming@bytedance.com> <20220721040439.2651-9-zhouchengming@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220721040439.2651-9-zhouchengming@bytedance.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 21, 2022 at 12:04:38PM +0800, Chengming Zhou wrote: > PSI accounts stalls for each cgroup separately and aggregates it > at each level of the hierarchy. This may case non-negligible overhead > for some workloads when under deep level of the hierarchy. > > commit 3958e2d0c34e ("cgroup: make per-cgroup pressure stall tracking configurable") > make PSI to skip per-cgroup stall accounting, only account system-wide > to avoid this each level overhead. > > For our use case, we also want leaf cgroup PSI accounted for userspace > adjustment on that cgroup, apart from only system-wide management. I hear the overhead argument. But skipping accounting in intermediate levels is a bit odd and unprecedented in the cgroup interface. Once we do this, it's conceivable people would like to do the same thing for other stats and accounting, like for instance memory.stat. Tejun, what are your thoughts on this?