linux-kernel - Re: [PATCH] x86/resctrl: mba_MBps: Fall back to total b/w if local b/w unavailable

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Message-ID: <CALPaoChftF-H6GauKq4-c_qBJP1GJbR3-ByE5krsaQF4y4y9oQ@mail.gmail.com>
Date:   Wed, 25 Oct 2023 14:46:53 +0200
From:   Peter Newman <peternewman@...gle.com>
To:     Tony Luck <tony.luck@...el.com>
Cc:     Fenghua Yu <fenghua.yu@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Jonathan Corbet <corbet@....net>,
        Shuah Khan <skhan@...uxfoundation.org>, x86@...nel.org,
        Shaopeng Tan <tan.shaopeng@...itsu.com>,
        James Morse <james.morse@....com>,
        Jamie Iles <quic_jiles@...cinc.com>,
        Babu Moger <babu.moger@....com>,
        Randy Dunlap <rdunlap@...radead.org>,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        patches@...ts.linux.dev
Subject: Re: [PATCH] x86/resctrl: mba_MBps: Fall back to total b/w if local
 b/w unavailable

Hi Tony,

On Tue, Oct 24, 2023 at 8:16 PM Tony Luck <tony.luck@...el.com> wrote:
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -418,6 +418,14 @@ static int __mon_event_count(u32 rmid, struct rmid_read *rr)
>         return 0;
>  }
>
> +static struct mbm_state *get_mbm_data(struct rdt_domain *dom_mbm, int rmid)
> +{
> +       if (is_mbm_local_enabled())
> +               return &dom_mbm->mbm_local[rmid];
> +
> +       return &dom_mbm->mbm_total[rmid];
> +}

That looks very similar to the get_mbm_state() function I added to
this same file recently:

https://lore.kernel.org/all/20221220164132.443083-2-peternewman%40google.com

I think the name you picked is misleadingly general. "local if
available, otherwise total" seems to be a choice specific to the mbps
controller. I think these functions should be reconciled a little
better.

Other than that, looks good.

Reviewed-by: Peter Newman <peternewman@...gle.com>