Re: [PATCH v3] blk-iocost: fix busy_level reset when no IOs complete

Jens Axboe
2026-03-31T19:56:58Z

On Tue, 31 Mar 2026 10:05:09 +0000, Jialin Wang wrote:
> When a disk is saturated, it is common for no IOs to complete within a
> timer period. Currently, in this case, rq_wait_pct and missed_ppm are
> calculated as 0, the iocost incorrectly interprets this as meeting QoS
> targets and resets busy_level to 0.
>
> This reset prevents busy_level from reaching the threshold (4) needed
> to reduce vrate. On certain cloud storage, such as Azure Premium SSD,
> we observed that iocost may fail to reduce vrate for tens of seconds
> during saturation, failing to mitigate noisy neighbor issues.
>
> [...]

Applied, thanks!

[1/1] blk-iocost: fix busy_level reset when no IOs complete
commit: f91ffe89b2016d280995a9c28d73288b02d83615

Best regards,
--
Jens Axboe