From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=95.215.58.250 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794229567; b=CwD+QtCXoJyAiM48wiQEqZksfgckE7PijJJZ/9dJm1fkRdWgPQx9aMYihv4IXeg1yFET WD11rFDET8Hm9jufshd4l7pSDCP7K5QhjRglPhn05qSLNAjD2KncOScvK5mE+n+5/6mB8 AkFdAzWcN1EOvBPScEgW9RcA92d3SO6J1ZqjMfEkrnDQtMu2YSB2wup9Qtfkh6HU9Xnw1 LyR+NZHmBoVlDM5RWEDnj9gl0Fn9OS+OFKdF2Y8byXJ64kxoBF9sSnslpakdf5UDEPITh rOGujjL2S2GvejkdtI/84jM4c0oyw0x2L2RxE0rs1Lwh4JxJ8BdWkiVjgzFU8ORrXeQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794229567; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:Message-ID:Date:MIME-Version:User-Agent: Cc:Subject:To:References:From:In-Reply-To:Content-Type: Content-Transfer-Encoding; bh=91+PrshXlXFSwP6fmMo9THAMzpUAzOQonBKifsHDzvY=; b=ABFnq09mpRDHSnW6VFhrMDdC4CHta2itPdkQpDVId1ER4onU+BVKhOnYnMnAZZ/AtfWR jlVA41ezD7+nwgSGcLe6fQmOQputVMFnSgMjrsxxdqf3O/cQaNJqp6FQuZ6wVFahXzdw/ bECT1UTAhyv7Wo02B9qPdX1f34FspwzlMbuzA9AJffGwT8ltFfeBy/xz8naeU9WY7FJVV bWOMIxVY7mlU1qVk/n01geFMKBzE+gwTcRmJHOyijT9TpofJpFpqsgT3/ZSfgnKeh0J06 0vhxVy2ij5uuOTPEKJz+qJPZd9PSjVUw4F8bk6HJJlxxNdw8Vkpv4haUtCNFpPXVVww== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=juxuwwtu; arc=none smtp.remote-ip=95.215.58.250 Received: from mta1.migadu.com (out-250.mta1.migadu.com [95.215.58.250]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1B09C606A323 for ; Mon, 9 Nov 2026 13:06:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 1B09C606A323 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=juxuwwtu X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=Vb2HvE4C+LsP6a08cxDbF41GOuV0T8q7dEJG6iihUxU=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1794229564; v=1; x=1794834364; b=juxuwwtuNfT6JUHX/dnWiiVTAbISIOKR6zjKvWh9biWy5FMYT++3zsr7afcvaLT8z4Cp407f JeWQtdZOwYiJ2XECrMCj/UkU9DJN1P6wE7xS12jhcs2Vi/Yt6AjVhIC7902LBE1SQql8snKJ9wW +Xe1au2SvzOSZyctSVCRmhuo= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 7c06950158a956d2; Mon, 09 Nov 2026 13:06:03 +0000 X-Mizu-Trace-ID: 7c06950158a956d2 X-Migadu-Flow: FLOW_OUT Message-ID: <1c4078e4-dd6a-4a70-bdda-d5cded19937a@linux.dev> Date: Mon, 9 Nov 2026 21:05:53 +0800 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Cc: cui.tao@linux.dev, 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, martin.lau@kernel.org, yonghong.song@linux.dev, mason@kernel.org, ihor.solodrai@linux.dev Subject: Re: [RFC PATCH v13 2/4] blk-iocost: add iocost_ioc_tick tracepoint for per-period device summary To: bot+bpf-ci@kernel.org, tj@kernel.org, josef@toxicopanda.com, axboe@kernel.dk, alexei.starovoitov@gmail.com References: <20261106122356.3224638-3-cui.tao@linux.dev> From: Tao Cui In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Hello, 在 2026/11/6 20:56, bot+bpf-ci@kernel.org 写道: >> blk-iocost: add iocost_ioc_tick tracepoint for per-period device summary > > TL;DR: Commit message only: it restates the code comment instead of giving the > motivation (monitoring without drgn) for the new iocost_ioc_tick tracepoint. Right, the changelog ended up restating the code comment. I'll rewrite it to lead with the motivation: the tracepoint gives a per-period summary so monitoring iocost doesn't require drgn. The emission semantics stay documented in the code. Thanks, Tao > Not a bug. > >> blk-iocost: add iocost_ioc_tick tracepoint for per-period device summary >> >> Add iocost_ioc_tick, emitted once per period from ioc_timer_fn() with >> the overall controller state: period_us, vrate, busy_level, active iocg >> count and usage percentage. busy_level, cur_period, nr_active and >> usage_us_sum are complete at the emission point. usage is wall time >> over wall time, summed over iocgs, and is not capped at 100. vrate and >> period_us reflect the current controller state, which an io.cost.qos >> write may have changed mid-period. >> >> The event fires every period the controller is running, including >> steady states, plus one final tick before the controller goes idle, so >> the transition to dormancy is directly visible. The active iocg count >> is only gathered when the tracepoint is enabled. >> >> Suggested-by: Tejun Heo >> Signed-off-by: Tao Cui > > this isn't a bug, but the middle of the first paragraph ("busy_level, > cur_period, nr_active and usage_us_sum are complete at the emission point > ... which an io.cost.qos write may have changed mid-period") restates the > block comment added above the tracepoint call in ioc_timer_fn() almost word > for word. > > The reason for adding the event only appears in the comment in > include/trace/events/iocost.h ("so basic monitoring doesn't require drgn"). > > Could the changelog say why a per-period summary event is needed, for > example the monitoring-without-drgn motivation, rather than repeating the > code comment? > > > --- > AI reviewed your patch. Please fix the bug or email reply why it's not a bug. > See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md > > CI run summary: https://github.com/kernel-patches/bpf/actions/runs/42219005018