From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f202.google.com (mail-pf1-f202.google.com [209.85.210.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 465C31CD0C for ; Mon, 14 Jul 2025 04:44:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752468292; cv=none; b=JUkwtSy1KO5tZejN0wZkGDsOnZT6R3ebjdXRRClvhK0wpQsi3M9Se16pUCBo0WEKdErLdnvo2yojBfT4qp1fTS7d5drhuvWjGQ5iPlxmB08QUUZQdta1t0v8/byVsM3jR96mdOmLqWdK4hGlzOeEXzSBvOqDMvR6Pz9CnOREKws= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752468292; c=relaxed/simple; bh=5vNg5iLm5fQUUSPoWLFmK0LPoRl1f1jq9DvfznsWj1k=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=dVgtLE/JiM1ACEZEs99kU34ovTlpiFSvExyzJBX7N5+bwfDuzNjxwRWgH+NriHoqYFIWV5YvOZ6E17fq6/JlRJTQcRz36YSQj7U0AZCxO8LYG9vTelCZuxX4XDnJ73/iL1VZxLwWqPPCi7/kl8e7TOnnOriMN8f+BrL4Y8KYDrs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--ynaffit.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=QVivIINL; arc=none smtp.client-ip=209.85.210.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--ynaffit.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="QVivIINL" Received: by mail-pf1-f202.google.com with SMTP id d2e1a72fcca58-74ea83a6c1bso1724670b3a.0 for ; Sun, 13 Jul 2025 21:44:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1752468290; x=1753073090; darn=vger.kernel.org; h=cc:to:from:subject:message-id:user-agent:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to; bh=vz4nZeT2Phnj2r45yuIHWOY+oW8/KY+q0YqmSchxW00=; b=QVivIINLKE0CEJZ/0Rs8RcPTHlPb50OyFBt0X7jS835PVSEYzQaAh1Tzd5Frh7SPbE MuBjE9Ju3oJIeGOWaRXDbVXIX3tGcjxQStNYpaaxeCkm+xAAWepvwRxYb/IwgpzLG+Wc 8CJM5L/4+i1PQaSgPHbO0rMgBZLuSTj94jrZJcM/L4FknHvHhSLB+7Vut3L9hWs6CgLW PizwcmxOmH9mOZznkuMO1zYZNHRQgDuJLTaAflSNMqzOUi6s2+PEph983XGrckB0ABxD E2Q6aY36Wo6oePbTHu2ThaePuB7PUinJONAouQispQzlJm8OtIGyWAKIvnOPsFXH/gEU t84w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1752468290; x=1753073090; h=cc:to:from:subject:message-id:user-agent:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=vz4nZeT2Phnj2r45yuIHWOY+oW8/KY+q0YqmSchxW00=; b=HFZms1nFBIGGEJbNIEQAp8EUlReUM0Ddv9INIEIwOA5qjHiE13RYWM4IPJsadbEVp/ 9jpGqu8trBwvDKFy+jS2MA1hm3u8AVeVTucqV5OepewbtiXnL1Tg/NK8uDGeYtST2eYE CDx7yQZ2+eBjwxK5pANvEGpqr96gKaLyuWfhN6To/Rh0glZQSWDI47IhCxEXYEV1Tzv+ aijM8Zy02A0X4mky1KpTGQ+Jx0exingwtgzU/0OR55DjgZHk5mf77pbyYSd70biBUAIL gOu06uWUjfBnqilqFSbMU4VBeSQYxMx5qnre+X8o95OtovPVxDGpPZ0/Arc2dP7jQrY7 aDhA== X-Gm-Message-State: AOJu0YzVkFh0e0Z15gZzXc0OEIKWeDxJsVhBAvLTwtCYwmCjprf+j8ZR GmK2a/rElMFGrTnKGGrOcKIReZ/Zs9d63yWxGXIh9QUqQPk8zsNpyKbhuwhxLprTB7LJPDR9qRX cRZI0b6Wq+g== X-Google-Smtp-Source: AGHT+IHS8Q/px8WH9ZbMmObz8rlW7f6xuLYox5HUzwM+jzX5Ungse5eiCulnCr9QVrut7RAYQNYZbnb9n6yx X-Received: from pfble3.prod.google.com ([2002:a05:6a00:4fc3:b0:748:f4a1:ae2e]) (user=ynaffit job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:23c6:b0:742:aecc:c47c with SMTP id d2e1a72fcca58-74ee0ab59d6mr13933650b3a.7.1752468290477; Sun, 13 Jul 2025 21:44:50 -0700 (PDT) Date: Sun, 13 Jul 2025 21:44:48 -0700 In-Reply-To: (Tejun Heo's message of "Fri, 27 Jun 2025 09:01:32 -1000") Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250603224304.3198729-3-ynaffit@google.com> User-Agent: mu4e 1.12.9; emacs 30.1 Message-ID: Subject: Re: [RFC PATCH] cgroup: Track time in cgroup v2 freezer From: Tiffany Yang To: Tejun Heo Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, kernel-team@android.com, John Stultz , Thomas Gleixner , Stephen Boyd , Anna-Maria Behnsen , Frederic Weisbecker , Johannes Weiner , "Michal =?utf-8?Q?Koutn=C3=BD?=" , "Rafael J. Wysocki" , Pavel Machek , Roman Gushchin , Chen Ridong , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes Hello! > ... > Glad that worked out, but I'm curious what are the involved time scales. > Let's say you get things off by some tens of msecs, or maybe even > hundreds, > does that matter for your purpose? Our wotchdog timers are on the order of a few seconds. Tens of msecs would be acceptable, but I think variances of hundreds of msecs would be large enough to cause issues. I mainly wanted to include the rough numbers in case anybody was curious about the actual magnitude of the offsets (if they wanted this accounting for a different use case, for example). > While it's not my call, I'm not necessarily against. However, as you noted > in another reply, the challenge is that there are multiple states and it's > not clear what combinations would be useful for whom. When/if we encounter > more real world use cases tha twould require these numbers, they may shed > light on what the right combination / interface is. IOW, I'm not sure this > is a case where adding something preemptively is a good idea. Ack. The per-cgroup accounting gets us most of the way there, so I'll be sending out that updated version shortly! I agree that another relevant use case would be immensely helpful for figuring out a way to describe the broader problem we are trying to solve and what shape a solution should take. Thank you for your feedback and for helping me to arrive at (what I hope is) a reasonable approach. -- Tiffany Y. Yang