From: Tejun Heo <tj@kernel.org>
To: Tao Cui <cui.tao@linux.dev>
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 <cuitao@kylinos.cn>
Subject: Re: [RFC PATCH v6 3/5] blk-iocost: add iocost_ioc_tick tracepoint for per-period device summary
Date: Mon, 21 Sep 2026 09:37:16 -1000 [thread overview]
Message-ID: <7203f0453d62336bb1ca712c8e7cf569@kernel.org> (raw)
In-Reply-To: <20260918055001.1273840-4-cui.tao@linux.dev>
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
next prev parent reply other threads:[~2026-09-21 19:37 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-18 5:49 [RFC PATCH v6 0/5] blk-iocost: BPF struct_ops cost model Tao Cui
2026-09-18 5:49 ` [RFC PATCH v6 1/5] blk-iocost: add BPF struct_ops cost model support Tao Cui
2026-09-21 19:37 ` Tejun Heo
2026-09-22 13:17 ` Tao Cui
2026-09-18 5:49 ` [RFC PATCH v6 2/5] selftests/bpf: add iocost cost model test Tao Cui
2026-09-18 5:49 ` [RFC PATCH v6 3/5] blk-iocost: add iocost_ioc_tick tracepoint for per-period device summary Tao Cui
2026-09-21 19:37 ` Tejun Heo [this message]
2026-09-22 13:18 ` Tao Cui
2026-09-18 5:50 ` [RFC PATCH v6 4/5] selftests/bpf: add multi-stream sequentiality example model Tao Cui
2026-09-18 5:50 ` [RFC PATCH v6 5/5] docs: cgroup-v2: document io.cost model=<name> binding Tao Cui
2026-09-21 19:37 ` [RFC PATCH v6 0/5] blk-iocost: BPF struct_ops cost model Tejun Heo
2026-09-22 13:11 ` Tao Cui
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