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

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Date:   Wed, 25 Oct 2023 23:06:20 +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 Wed, Oct 25, 2023, 21:38 Tony Luck <tony.luck@...el.com> wrote:
>
> On Wed, Oct 25, 2023 at 02:46:53PM +0200, Peter Newman wrote:
>
> > > +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.
> >
>
> Peter (and Babu, who made the same point about get_mbm_state().
>
> Do you want to see your function extended to do the "pick an MBM event?"

What I meant was I think it would be enough to just give the function
you added a name that's more specific to the Mbps controller use case.
For example, get_mba_sc_mbm_state().

It's only problematic that you added a function with an equivalent
name to an existing function that does something different.

-Peter