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

[Moger, Babu]

Hi Tony,

On 10/25/2023 3:52 PM, Tony Luck wrote:
> On Wed, Oct 25, 2023 at 03:42:14PM -0500, Moger, Babu wrote:
> > I meant, I was thinking bit different.
> >
> > > You need these changes in only two functions, mbm_bw_count and
> > > update_mba_bw. You decide which event you want to use based on availability,
> > >
> > > Something like this. I updated mbm_bw_count.
> > >
> > > diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c
> > > b/arch/x86/kernel/cpu/resctrl/monitor.c
> > > index 0ad23475fe16..302993e4fbc3 100644
> > > --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> > > +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> > > @@ -436,8 +436,16 @@ static int __mon_event_count(u32 rmid, struct
> > > rmid_read *rr)
> > >    */
> > >   static void mbm_bw_count(u32 rmid, struct rmid_read *rr)
> > >   {
> > > -       struct mbm_state *m = &rr->d->mbm_local[rmid];
> > >          u64 cur_bw, bytes, cur_bytes;
> > > +       struct mbm_state *m;
> > > +       int evtid;
> > > +
> > > +       if (is_mbm_local_enabled())
> > > +               evtid = QOS_L3_MBM_LOCAL_EVENT_ID;
> > > +       else
> > > +               evtid = QOS_L3_MBM_TOTAL_EVENT_ID;
> > > +
> > > +       m = get_mbm_state(rr->d, rmid, evtid);
> Ok. Yes. That seems simpler.
>
> Maybe I should just set a global "mbm_evtid" at mount

Lets not make it global yet. This is only affecting couple of functions 
when mba_MPps is enabled.

> time. No need to check every time to see if is_mbm_local_enabled()
> somehow changed and local b/w measurements were suddenly
> available!

What changed suddenly? Can you please elaborate.

Thanks

Babu