Re: [PATCH v2] blk-ioprio: Introduce promote-to-rt policy

From: Bagas Sanjaya
Date: Wed Feb 22 2023 - 02:38:12 EST


On 2/20/23 20:54, Hou Tao wrote:
> diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
> index 74cec76be9f2..ccfb9fdfbc16 100644
> --- a/Documentation/admin-guide/cgroup-v2.rst
> +++ b/Documentation/admin-guide/cgroup-v2.rst
> @@ -2021,31 +2021,33 @@ that attribute:
> no-change
> Do not modify the I/O priority class.
>
> - none-to-rt
> - For requests that do not have an I/O priority class (NONE),
> - change the I/O priority class into RT. Do not modify
> - the I/O priority class of other requests.
> + promote-to-rt
> + For requests that have a no-RT I/O priority class, change it into RT.
"non-RT" maybe? Or the original wording is better?
> + Also change the priority level of these requests to 4. Do not modify
> + the I/O priority of requests that have priority class RT.>
> restrict-to-be
> For requests that do not have an I/O priority class or that have I/O
> - priority class RT, change it into BE. Do not modify the I/O priority
> - class of requests that have priority class IDLE.
> + priority class RT, change it into BE. Also change the priority level
> + of these requests to 0. Do not modify the I/O priority class of
> + requests that have priority class IDLE.
>
> idle
> Change the I/O priority class of all requests into IDLE, the lowest
> I/O priority class.
>
> + none-to-rt
> + Deprecated. Just an alias for promote-to-rt.
> +
> The following numerical values are associated with the I/O priority policies:
>
> -+-------------+---+
> -| no-change | 0 |
> -+-------------+---+
> -| none-to-rt | 1 |
> -+-------------+---+
> -| rt-to-be | 2 |
> -+-------------+---+
> -| all-to-idle | 3 |
> -+-------------+---+
> ++----------------+---+
> +| no-change | 0 |
> ++----------------+---+
> +| rt-to-be | 2 |
> ++----------------+---+
> +| all-to-idle | 3 |
> ++----------------+---+
>
> The numerical value that corresponds to each I/O priority class is as follows:
>
> @@ -2061,9 +2063,13 @@ The numerical value that corresponds to each I/O priority class is as follows:
>
> The algorithm to set the I/O priority class for a request is as follows:
>
> -- Translate the I/O priority class policy into a number.
> -- Change the request I/O priority class into the maximum of the I/O priority
> - class policy number and the numerical I/O priority class.
> +- If I/O priority class policy is promote-to-rt, change the request I/O
> + priority class to IOPRIO_CLASS_RT and change the request I/O priority
> + level to 4.
> +- If I/O priorityt class is not promote-to-rt, translate the I/O priority
> + class policy into a number, then change the request I/O priority class
> + into the maximum of the I/O priority class policy number and the numerical
> + I/O priority class.
>
> PID
> ---

The rest is LGTM.

--
An old man doll... just what I always wanted! - Clara