From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D148A19F422; Fri, 22 Aug 2025 17:51:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755885087; cv=none; b=EUFGqyqEsdEncMqu8nGJLfUrT/zIeDae3wmgU9jIuVHIfPauA1NKHBU8j2XQhLUkaHLfRGBEujI6DOaKThKucZlVCIg4KggJOqtuLVUVe1y9qXRLsyEEMiT1ykpqyAtu75SyxQc5u2wA1wMVburEfKMSlKkhwitLUCbwptG/Wqg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755885087; c=relaxed/simple; bh=aD8+ds7nYN/JrrUWGfgklx///DHtTRGvjBkMg7m1/78=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=pUHWdC2ucX7dHi4RV9rnm12rM4AOEIIIF3JItI/G1zbDpP3E2h7Y+UbxFxEYsHRNnt10ODMM/ev/b/WjE3+9OWRj6KIQD9khrybrmJ9uw7Ikn7sBj3GyAnQ1dn99AURxGwZLrFMkrIAoxw94teneD00dCcTJZ+L7igxrs1uS9BU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JVoud6mL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JVoud6mL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 332A5C4CEED; Fri, 22 Aug 2025 17:51:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755885086; bh=aD8+ds7nYN/JrrUWGfgklx///DHtTRGvjBkMg7m1/78=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=JVoud6mLg4D/K38Guig7VA3SOByS6iBZJyeyCIDZNZpG2wHqQU0Uaxh3ITW9UvCHv +DpH+5g2nlcZW4ho1/MgzraC2gUFGFx3Yn+qKxJ18rQUzSTxXlm0a9q2QZpqjQogiy fKWm6EbTdHvHpUTNPj+4TAkUqKrhP7LQGwLmGlwtigl2o/SMSEjrG7U10oYaHalgB8 XcM4i2GWwVe7ORmc2o28qLjEe1FRAPV9F2vzuQRKEINaAQfN5TsRGb6lhxQgIlAvDC araclU0fy5MQzvKr2igdhqozqMRH0Wce2yeP88SQ1FwK+t0HgGhGC0XeWX51FT3Y+P sdgmYL7kwQKSw== Date: Fri, 22 Aug 2025 07:51:25 -1000 From: Tejun Heo To: Tiffany Yang Cc: linux-kernel@vger.kernel.org, John Stultz , Thomas Gleixner , Stephen Boyd , Anna-Maria Behnsen , Frederic Weisbecker , Johannes Weiner , Michal =?iso-8859-1?Q?Koutn=FD?= , "Rafael J. Wysocki" , Pavel Machek , Roman Gushchin , Chen Ridong , kernel-team@android.com, Jonathan Corbet , Shuah Khan , cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v4 0/2] cgroup: Track time in cgroup v2 freezer Message-ID: References: <20250822013749.3268080-6-ynaffit@google.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250822013749.3268080-6-ynaffit@google.com> On Thu, Aug 21, 2025 at 06:37:51PM -0700, Tiffany Yang wrote: > Hello, > > The cgroup v2 freezer controller is useful for freezing background > applications so they don't contend with foreground tasks. However, this > may disrupt any internal monitoring that the application is performing, > as it may not be aware that it was frozen. > > To illustrate, an application might implement a watchdog thread to > monitor a high-priority task by periodically checking its state to > ensure progress. The challenge is that the task only advances when the > application is running, but watchdog timers are set relative to system > time, not app time. If the app is frozen and misses the expected > deadline, the watchdog, unaware of this pause, may kill a healthy > process. > > This series tracks the time that each cgroup spends "freezing" and > exposes it via cgroup.stat.local. Include several basic selftests to > demonstrate the expected behavior of this interface, including that: > 1. Freeze time will increase while a cgroup is freezing, regardless of > whether it is frozen or not. > 2. Each cgroup's freeze time is independent from the other cgroups in > its hierarchy. > > Thanks, > Tiffany > > Signed-off-by: Tiffany Yang Applied to cgroup/for-6.18. Let's address further issues incrementally. Thanks. -- tejun