linux-kernel - Re: [PATCH v10 10/10] x86/resctrl: Display RMID of resource group

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Date:   Fri, 22 Sep 2023 16:36:20 +0200
From:   Peter Newman <peternewman@...gle.com>
To:     Babu Moger <babu.moger@....com>
Cc:     corbet@....net, reinette.chatre@...el.com, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, fenghua.yu@...el.com,
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        paulmck@...nel.org, akpm@...ux-foundation.org,
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        peterz@...radead.org, jpoimboe@...nel.org, pbonzini@...hat.com,
        chang.seok.bae@...el.com, pawan.kumar.gupta@...ux.intel.com,
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Subject: Re: [PATCH v10 10/10] x86/resctrl: Display RMID of resource group

Hi Babu,

On Sat, Sep 16, 2023 at 12:42 AM Babu Moger <babu.moger@....com> wrote:
>
> In x86, hardware uses RMID to identify a monitoring group. When a user
> creates a monitor group these details are not visible. These details
> can help resctrl debugging.
>
> Add RMID(mon_hw_id) to the monitor groups display in resctrl interface.
> Users can see these details when resctrl is mounted with "-o debug" option.

When I reviewed this, I went through the whole series second-guessing
the wording above and wondering whether "monitoring groups" applied to
CTRL_MON groups.

I was able to confirm that mon_hw_id did appear and had a believable
value in CTRL_MON groups which had allocated monitors. (and I added
some comma-separated PID lists to the tasks node)

for the series:
Tested-By: Peter Newman <peternewman@...gle.com>

> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index a07fa4329b65..b4910892b0a6 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -296,6 +296,11 @@ struct rdtgroup {
>   *     --> RFTYPE_BASE (Files common for both MON and CTRL groups)
>   *         Files: cpus, cpus_list, tasks
>   *
> + *             --> RFTYPE_MON (Files only for MON group)

If monitoring is supported, all groups are MON groups. I think the
"only" above caused me to second guess whether this takes into account
CTRL_MON groups getting the RFTYPE_MON flag set dynamically.

However, I think the documentation above is still technically accurate.

for the series:
Reviewed-By: Peter Newman <peternewman@...gle.com>

Thanks!
-Peter