From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793218172; b=hRudOfgTkMbRbAezHyTwlW3eXNl6o9d7mMXh/Mp6fbqNykeGv4sjd4G7BsbDov2Ra7S+ fsHiFtw3YvyXtiTSl1ZgzxZmuoXDnlHJBrG3nH1x0s5NSITr9Gq2BnN5PXBjCwGfeGiP3 qbUQQea9F9UZiZRDaWOz49AWW/qlmCy/UkaOy+bAGyFjtL+fsIyW6Mjq8I/C4KbudH3Mr RtFe2LikNXtm6OQRvzB5ZkdaHGLsKXojE7/IIympyjgX1qWcZlYgpu10dSHtKYqM/douP hR02cQ/w7Gz6w+vjAnof8/wq51flh4MHVZQ/4wgdj20vh0E/wqzpPAyKWh9dqmm2k/g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793218172; h=Received:DKIM-Signature:Date:Message-ID:From:To:Cc:Subject: In-Reply-To:References:MIME-Version:Content-Type: Content-Transfer-Encoding; bh=Y9prV6WuIi15Ykaoy1sEEO6x+8TCFI9Z8BWNg0g0Ywk=; b=2wNocvp8hrFdtADf8lYBgppPZGx21wOmgOfGEfgVue8It1wbNCL2zI9JSDkWzuFyUQcB sXyDhaaM3G+lutP19LjKK2c8shLX75TQ1EUIAOH620Cwf7VxhuhimLY4PPVCUivSRK22u DQROE4qX9/8cVuOTLIt1lju3JzpapxAG4ISmuvPsLlg8jMeyDSxPGEhD1H9zoAtnU46uY L3J6+SWeDjCumsQJmMr3Kp7TAIyE4K0EGsCtnhL3EXcWaMhz4dkn6hh3tZsUfoEEbryWJ SCa9swOMQgopdZShYSYEe22DYqP7vRCQJXl5vnZWAZtFwhQsV+JgiORLaYv97hs+Ocg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="WND6t1/j"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 56D1260A3820; Wed, 28 Oct 2026 20:09:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=WND6t1/j Received: by smtp.kernel.org (Postfix) with ESMTPSA id E4ECD1F01829; Wed, 28 Oct 2026 20:09:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793218172; bh=Y9prV6WuIi15Ykaoy1sEEO6x+8TCFI9Z8BWNg0g0Ywk=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=WND6t1/jTFscSVNiNiVqFI+25ygKV43rBTw/IGzypSYvTe95dJR8SahVRynocJz6s IJme8Tw+bnsZrayFVEW9e/VCfLhvsXlE3jsnYpM7xzoAgfiinqstsy/fdVL7hEidlX ey4HcPH5A4Q6oRiAihCsRSxcGo27G7yJXQg6Sj9M/kHUGjYDznI9fyLcAWy2AGc7er 8K2JehtT03S1rIasywLfEZEeS9QQYmmczaXqBM53X4HEH5MGRXpJR5k4YNVaYs0VI9 NfGWP8hL2r3gR+K/tPfXUC5H86uJLwLcTChcka8RBIZfc44QgUktahYa5jvvglMI1v YSLmq2+fp7B5A== Date: Wed, 28 Oct 2026 10:09:31 -1000 Message-ID: <72deb196d0dfc413a48f0739013bc610@kernel.org> From: Tejun Heo To: Tao Cui Cc: josef@toxicopanda.com, axboe@kernel.dk, cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, andrii@kernel.org, eddyz87@gmail.com, ast@kernel.org, daniel@iogearbox.net, linux-kselftest@vger.kernel.org, cuitao@kylinos.cn, ameryhung@gmail.com, alexei.starovoitov@gmail.com Subject: Re: [PATCH 5/5] docs: cgroup-v2: document the iocost BPF cost model attachment In-Reply-To: <20261028143534.135968-6-cui.tao@linux.dev> References: <20261028143534.135968-1-cui.tao@linux.dev> <20261028143534.135968-6-cui.tao@linux.dev> X-Mailing-List: bpf@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Hello, Tao. On Wed, Oct 28, 2026 at 10:35:34PM +0800, Tao Cui wrote: > + When CONFIG_BLK_CGROUP_IOCOST_BPF is enabled, a BPF cost > + model can be bound to a device by attaching an Users can't select CONFIG_BLK_CGROUP_IOCOST_BPF. > + Only detaching removes the model, after which "model=bpf" > + fails and the device prices with the builtin model again. > + Device removal ejects the attached model as well, while the > + struct_ops link remains until userspace destroys it. "ctrl" "Only detaching removes the model" is followed by "Device removal ejects the attached model as well". > + accepts only "auto" and "user" and never selects a model. It > + keeps describing the builtin coefficients, which take effect > + again when switched back. The automatic profile stepping does > + not switch profiles while the BPF model is in use; as with > + user-set parameters, the profile selected from the device > + class still applies. cgroup-v2.rst doesn't describe automatic profile stepping anywhere else. > + defined. They remain readable and writable while "model" is > + "bpf" but take effect only after switching back to "linear". The builtin coefficients taking effect again after switching back is already said above. Thanks. -- tejun