From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-177.mta0.migadu.com [91.218.175.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6341848F820 for ; Thu, 10 Sep 2026 12:58:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.177 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789045129; cv=none; b=jqof3+XneIMI+Sv50J2eiIT58kzk+C2QQC7Soyl9tfxdCmM+mJkZXLYd2B+XB7nPxGydDSbQj1fxHobO4GdRbVDfc464l0i4Rn/4YyAY3RWKBnQ/d6dDjjTVavvL0nf2deQFh8O5HkNhqeRkXKw2TXLgMBf8SS4vx+g9KB4em3s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789045129; c=relaxed/simple; bh=0fJmoDVgXoCT6wg71trk+r4GMKglV+8D+hnxVKMiMh8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=gZrbdwtcPOh+8Y+5BvzRjNElkYIYspozVBxSbCxUj/Th7J3towrfBXYEHhH023pUvsebT6ULvHMbHBStWFTF/Oqs9Ddautv+b0S5YuXBHWp9VUDFMZ7atGnk8zQs7PC/23uDStO9IbG4mcJ38LAQX7SFqQC79kqDnB6ALa0R1e0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=j6axNBtV; arc=none smtp.client-ip=91.218.175.177 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) header.d=linux.dev header.i=@linux.dev header.b="j6axNBtV" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=0fJmoDVgXoCT6wg71trk+r4GMKglV+8D+hnxVKMiMh8=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1789045123; v=1; x=1789649923; b=j6axNBtVTV97ABwliYcSHsaak+4cZhBU4WSPGel1gWMOo3ldJzE9nlcG2ldSXxj8kz3F5MEM z594oHJBO6Yqv9UgLriMM0qEUhIq1CH4uMnQlDbT4PN8o4zFGBN/9aEPHsbcKZLDA0VMglRUXZp N8TBE7oHd+qGYsfZmPLFe1+s= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 4fa7f97bbfba81e3; Thu, 10 Sep 2026 12:58:43 +0000 X-Mizu-Trace-ID: 4fa7f97bbfba81e3 X-Migadu-Flow: FLOW_OUT From: Tao Cui To: tj@kernel.org, josef@toxicopanda.com, axboe@kernel.dk Cc: cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, andrii@kernel.org, ast@kernel.org, daniel@iogearbox.net, linux-kselftest@vger.kernel.org, cui.tao@linux.dev, cuitao@kylinos.cn Subject: [RFC PATCH v2 3/5] blk-iocost: add iocost_ioc_tick tracepoint for per-period device summary Date: Thu, 10 Sep 2026 20:58:15 +0800 Message-ID: <20260910125817.223354-4-cui.tao@linux.dev> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260910125817.223354-1-cui.tao@linux.dev> References: <20260910125817.223354-1-cui.tao@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Tao Cui The existing iocost tracepoints are state-change driven: vrate_adj fires only when the adjustment logic runs, inuse_* only on surplus state transitions, activate/idle only on cgroup state changes. In a steady state none of them fire. The only other way to observe the controller (period length, vrate, busy level, active cgroup count, device utilization) is iocost_monitor.py, which reads kernel memory through drgn and is not usable in most production environments. Add iocost_ioc_tick, emitted once per period from the tail of ioc_timer_fn() with the overall controller state: period_us, vrate, busy_level, active iocg count, usage percentage and running state. It fires every period the controller runs, including steady states, plus one final tick before the controller goes idle, which makes dormancy (e.g. a device saturated entirely by uncharged IO) directly visible. At the default period this is a couple of events per second per device; the cost is zero while the static key is off. Signed-off-by: Tao Cui --- block/blk-iocost.c | 5 +++++ include/trace/events/iocost.h | 40 +++++++++++++++++++++++++++++++++++ 2 files changed, 45 insertions(+) diff --git a/block/blk-iocost.c b/block/blk-iocost.c index 182601ad783f..bccdbd2496d8 100644 --- a/block/blk-iocost.c +++ b/block/blk-iocost.c @@ -2244,6 +2244,7 @@ static void ioc_timer_fn(struct timer_list *timer) struct ioc_now now; LIST_HEAD(surpluses); int nr_debtors, nr_shortages = 0, nr_lagging = 0; + int nr_active = 0; u64 usage_us_sum = 0; u32 ppm_rthr; u32 ppm_wthr; @@ -2280,6 +2281,8 @@ static void ioc_timer_fn(struct timer_list *timer) u64 vdone, vtime, usage_us; u32 hw_active, hw_inuse; + nr_active++; + /* * Collect unused and wind vtime closer to vnow to prevent * iocgs from accumulating a large amount of budget. @@ -2466,6 +2469,8 @@ static void ioc_timer_fn(struct timer_list *timer) ioc_refresh_vrate(ioc, &now); } + trace_iocost_ioc_tick(ioc, nr_active, usage_us_sum); + spin_unlock_irq(&ioc->lock); } diff --git a/include/trace/events/iocost.h b/include/trace/events/iocost.h index e772b1bc60d6..2b9ff348a4f5 100644 --- a/include/trace/events/iocost.h +++ b/include/trace/events/iocost.h @@ -178,6 +178,46 @@ TRACE_EVENT(iocost_ioc_vrate_adj, ) ); +/* + * Periodic per-device summary, emitted once per period from the tail of + * ioc_timer_fn(). Unlike the state-change events above, this fires every + * period the controller is running, including steady states, and carries + * the overall controller state so basic monitoring doesn't require drgn. + */ +TRACE_EVENT(iocost_ioc_tick, + + TP_PROTO(struct ioc *ioc, int nr_active, u64 usage_us_sum), + + TP_ARGS(ioc, nr_active, usage_us_sum), + + TP_STRUCT__entry ( + __string(devname, ioc_name(ioc)) + __field(u32, period_us) + __field(u64, vrate) + __field(int, busy_level) + __field(int, nr_active) + __field(u32, usage_pct) + __field(int, running) + ), + + TP_fast_assign( + __assign_str(devname); + __entry->period_us = ioc->period_us; + __entry->vrate = ioc->vtime_base_rate; + __entry->busy_level = ioc->busy_level; + __entry->nr_active = nr_active; + __entry->usage_pct = ioc->period_us ? + div_u64(usage_us_sum * 100, ioc->period_us) : 0; + __entry->running = ioc->running; + ), + + TP_printk("[%s] period=%uus vrate=%llu busy=%d active=%d usage=%u%% running=%d", + __get_str(devname), __entry->period_us, __entry->vrate, + __entry->busy_level, __entry->nr_active, __entry->usage_pct, + __entry->running + ) +); + TRACE_EVENT(iocost_iocg_forgive_debt, TP_PROTO(struct ioc_gq *iocg, const char *path, struct ioc_now *now, -- 2.43.0