linux-kernel - Re: [PATCH v2 3/3] x86/resctrl: Add "*" shorthand to set minimum io

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Message-ID: <fpfpi7ol3ohcpmix6jy5ammn3tyereltuuyu2ol4iyld46hjvl@xnerfkdmd4xp>
Date: Thu, 18 Dec 2025 19:26:09 -0500
From: Aaron Tomlin <atomlin@...mlin.com>
To: "Moger, Babu" <bmoger@....com>
Cc: tony.luck@...el.com, reinette.chatre@...el.com, Dave.Martin@....com, 
	james.morse@....com, babu.moger@....com, tglx@...utronix.de, mingo@...hat.com, 
	bp@...en8.de, dave.hansen@...ux.intel.com, sean@...e.io, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/3] x86/resctrl: Add "*" shorthand to set minimum
 io_alloc CBM for all domains

On Thu, Dec 18, 2025 at 03:32:56PM -0600, Moger, Babu wrote:
> Can't we just simplify to this patch without adding new data structures?

Hi Babu,

Indeed, we certainly can.

> diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c
> index f7608121f5e3..d113d8a3ee02 100644
> --- a/fs/resctrl/ctrlmondata.c
> +++ b/fs/resctrl/ctrlmondata.c
> @@ -874,6 +874,7 @@ static int resctrl_io_alloc_parse_line(char *line,
> struct rdt_resource *r,
>         struct rdt_ctrl_domain *d;
>         char *dom = NULL, *id;
>         unsigned long dom_id;
> +       bool update_all;
> 
>  next:
>         if (!line || line[0] == '\0')
> @@ -881,14 +882,18 @@ static int resctrl_io_alloc_parse_line(char *line,
> struct rdt_resource *r,
> 
>         dom = strsep(&line, ";");
>         id = strsep(&dom, "=");
> -       if (!dom || kstrtoul(id, 10, &dom_id)) {
> +       update_all = false;
> +
> +       if (id && *id == '*') {
> +               update_all = true;
> +       } else if (!dom || kstrtoul(id, 10, &dom_id)) {
>                 rdt_last_cmd_puts("Missing '=' or non-numeric domain\n");
>                 return -EINVAL;
>         }
> 
>         dom = strim(dom);
>         list_for_each_entry(d, &r->ctrl_domains, hdr.list) {
> -               if (d->hdr.id == dom_id) {
> +               if (update_all || (d->hdr.id == dom_id)) {
>                         data.buf = dom;
>                         data.mode = RDT_MODE_SHAREABLE;
>                         data.closid = closid;

The above is suitable. I will prepare a follow-up series once our wider
discussion has concluded and we have reached a consensus on the
architectural direction.


Kind regards,
-- 
Aaron Tomlin

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