From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 5F4C13AFD08; Mon, 21 Sep 2026 19:37:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790019438; cv=none; b=JzJJ33bjkIa7SSDuboj9Jt7RYFVevDmHaUrt5wvMJ7aoHR9VS0yjiA9TM8TDC+o28nfELh5QL/HpyhQT0Z+BPj28zX8yUHluhr4z4zP8ODxbJ48WVGhO6YvkvAhZ4R7hhwvgq9WK2zEpZwhzHo9ey8xwPVedJuWUf27F+tSi5Fk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790019438; c=relaxed/simple; bh=UEhp+M6uzGZAoB1SP2XF8MMdYUEVtqe4WaLWbKs/7U4=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: Content-Type:MIME-Version; b=D4yCKjM+dCxXSvVe1u8FPNVewozDrn+xjFdGzk3cmB8DYcW1N7msFDmrfokvAMTISJyPIwdgEBRMVny+11tm0v51uW7qBmoGpPqZv4DmrzMqoKqygb0lbymbT1zKl+yDJ/OudbiSYWuFfqIjUiUWQrEvheG5kIajjDpVSqaDwwA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=b68eWj3Z; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="b68eWj3Z" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D90E21F000FF; Mon, 21 Sep 2026 19:37:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790019437; bh=D4BUo3gWAt0lmzTIDyeCjhR1jQ3mSGxnxe6GUia/2CQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=b68eWj3ZD68iF7854hRzWquQQGmKfF6p3mP1x5Jb4S1039H7EnPt/hUPkCRZN8glz B32zhonmRE88enzDEdMg86t2B06HC54jGkUl4QY4pvAI1ASQS9NYehm+z4feP8ktEu uj/raKc6UlTeCUenbXq8VQzvyeCa92EKu7M5IT6mygzj3O4wTiditpqBeydFao7Z11 rG2ZguL6UOI/cdkx3wsQcy9UKLnHCqbQkHZ8y0sI1P31IQY4F0QFvcl7ovaTnqfxxA c8zl5GeTxy/ncdPLT6AuYEpsaYxUI3+Jsr6v13BJDUmmoG0YgaxYjw43pTLO/bsX0O Uxz04TGI2Ezyw== Date: Mon, 21 Sep 2026 09:37:16 -1000 Message-ID: <7203f0453d62336bb1ca712c8e7cf569@kernel.org> From: Tejun Heo To: Tao Cui Cc: tj@kernel.org, josef@toxicopanda.com, axboe@kernel.dk, ameryhung@gmail.com, 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, Tao Cui Subject: Re: [RFC PATCH v6 3/5] blk-iocost: add iocost_ioc_tick tracepoint for per-period device summary In-Reply-To: <20260918055001.1273840-4-cui.tao@linux.dev> References: <20260918055001.1273840-1-cui.tao@linux.dev> <20260918055001.1273840-4-cui.tao@linux.dev> Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Hello, Tao. On Fri, 18 Sep 2026 13:49:59 +0800, Tao Cui wrote: > + /* > + * vrate and period_us change right below; snapshot the values > + * this period ran in so the tick below reports the period's own > + * parameters instead of the next period's. > + */ > + tick_period_us = ioc->period_us; > + tick_vrate = ioc->vtime_base_rate; Everything the tick reports is already final at this point. busy_level was just computed, running and cur_period haven't changed yet, and nr_active and usage_us_sum are complete. Can you emit the tracepoint here instead and drop the snapshots? The event can then read the fields directly and the only cost outside the static key is the nr_active increment. Looks fine otherwise. Thanks. -- tejun