Re: [PATCH v4] Docs/admin-guide/cgroup-v2: document io.latency rotational vs non-rotational behavior

Tejun Heo <[email protected]> Sun, 02 Aug 2026 11:32:49 -1000
Newsgroups org.kernel.vger.cgroups,org.kernel.vger.linux-block,org.kernel.vger.linux-doc,org.kernel.vger.linux-kernel
Message-ID <[email protected]>
On Tue, Jul 28, 2026 at 05:57:07PM +0800, Tao Cui wrote:
> io.latency is documented only in terms of average latency and the avg_lat
> stat, which matches rotational devices.  On non-rotational devices a group
> misses its target once enough of the IOs in the window individually exceed
> it, and io.stat reports missed/total rather than avg_lat/win.
>
> Describe both cases: how a miss is detected, note that the avg_lat tuning
> guidance is rotational-only, and update the io.stat field list (mark
> avg_lat/win as rotational-only, document missed/total).
>
> Acked-by: Michal Koutný <[email protected]>
> Signed-off-by: Tao Cui <[email protected]>

Applied to cgroup/for-7.2-fixes.

Thanks.

--
tejun