Re: [RFC PATCH v6 3/5] blk-iocost: add iocost_ioc_tick tracepoint for per-period device summary

[Tejun Heo]

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