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 DB1E625FA29 for ; Tue, 3 Feb 2026 20:26:20 +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=1770150380; cv=none; b=HJun03rqUTIE3udVi+/LPEPZjrpXqsMGSNMxYkFadl1JiiNmcwfqThuLz+hisUEySOsnQc/r4RM3P7wsOrRk1GvFsfDyW7RlhnpOUsBnaU46vbwltOwhMKuPUPCCC09/7TofijhY3GJyefEnUqgK+dT+bvvr5/s7+ohfToEjMbg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770150380; c=relaxed/simple; bh=67UwMTEkJDoE0Rhxh75e3aXqro7WeuDpj2Lx0CRSGoE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=HWk6xx071appkLYDRrXwen7R8WIkHB4R6sDjy9BdQm4vXqf9FqBAZXlLOBOSiT3zKmPOqN4Ezcy5Fqqp1bQLCruy1InlOjPkiBtyb58IXer1BVTxxPPMF8pB8bNPAAupd5o0RBBWhhB4brsfRnGL7V4wa+mzQiM9b9w7pLyOpF4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fCU9gE1F; 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="fCU9gE1F" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 550AAC116D0; Tue, 3 Feb 2026 20:26:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770150380; bh=67UwMTEkJDoE0Rhxh75e3aXqro7WeuDpj2Lx0CRSGoE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fCU9gE1FPalgS1P1JE5z36qmh6JvP3Y+8Plog0BEvl5FkBlS/j1X0lQ/YTJ+jZS3O 9MmRm/7Rg+8HgpQfjhleVrh0SKZpYf32bdfPspEYQSFilyqhr0OCO+sbKUBtLX2RAz pkOonVzFZgLXZaxEsie1UB+juIvrbsMTz1XdPg9drtnlRbFGdw2v1phwE4LQ08zbWg vqgZg/ACnG8XUVwfmN8wDHYPQORnPAtQANFLXcebujbIl+W98OQsQlYVwNHKg65u4M c1yqDPRizykeRw6GaxzA2Acv/RM421Yb9iTi5oalSmddstSQAFSRTUFvOcq7Pa/y88 ieUb+2/FKiqpA== Date: Tue, 3 Feb 2026 10:26:19 -1000 From: Tejun Heo To: Rohan Kakulawaram Cc: bpf@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , ohn Fastabend , KP Singh , Stanislav Fomichev , Jiri Olsa , Roman Gushchin , Matt Bobrowski , Josh Don Subject: Re: [RFC PATCH bpf-next] bpf: ephemeral cgroup BPF control programs Message-ID: References: <20260203102058.41030-1-rohanka@google.com> Precedence: bulk X-Mailing-List: bpf@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: <20260203102058.41030-1-rohanka@google.com> Hello, Rohan. On Tue, Feb 03, 2026 at 10:20:55AM +0000, Rohan Kakulawaram wrote: ... > One of the main gaps in achieving these ends, however, is that > there is no infrastructure that supports exposing per cgroup data > via file paths that mirror the cgroupfs hierarchy. This would > allow for a unified source of truth as it relates to accessing > various streams of data related to cgroups. It is important to > note that we would want the fate of these ephemeral files to be > tied to the manipulation of the cgroup tree, such as exposing/ > deleting files when creating/removing cgroups respectively. > Cgroup iterators can mimic some of this functionality through > bpffs pins but lack the dynamism of the listed approach. On one hand, I think why not, but at the same time, I'm having a hard time why this would need to be on some file system. After all, we're talking about BPF, there are numerous way lower overhead ways to do bi-directional communication - shared pinned maps, BPF upcalls, BPF seqfile iterator, ring buffer based interface and so on. Can you elaborate why this *needs* to be a separate file interface? Note that this doesn't really expand what BPF progs can do with cgroups. The only thing being added is a different and not-particularly-efficient way to communicate with BPF progs. Thanks. -- tejun