Re: [PATCH v6 03/10] perf/x86/rapl: Remove the cpu_to_rapl_pmu() function

[Zhang, Rui]

On Mon, 2024-10-28 at 14:49 +0530, Dhananjay Ugwekar wrote:
> Hello Gautham,
> 
> On 10/28/2024 2:23 PM, Gautham R. Shenoy wrote:
> > Hello Dhananjay,
> > 
> > On Fri, Oct 25, 2024 at 11:13:41AM +0000, Dhananjay Ugwekar wrote:
> > > Prepare for the addition of RAPL core energy counter support.
> > > Post which, one CPU might be mapped to more than one rapl_pmu
> > > (package/die one and a core one). So, remove the
> > > cpu_to_rapl_pmu()
> > > function.
> > > 
> > > Signed-off-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@xxxxxxx>
> > > ---
> > >  arch/x86/events/rapl.c | 19 ++++++-------------
> > >  1 file changed, 6 insertions(+), 13 deletions(-)
> > > 
> > > diff --git a/arch/x86/events/rapl.c b/arch/x86/events/rapl.c
> > > index f70c49ca0ef3..d20c5b1dd0ad 100644
> > > --- a/arch/x86/events/rapl.c
> > > +++ b/arch/x86/events/rapl.c
> > > @@ -162,17 +162,6 @@ static inline unsigned int
> > > get_rapl_pmu_idx(int cpu)
> > >                                         
> > > topology_logical_die_id(cpu);
> > >  }
> > >  
> > > -static inline struct rapl_pmu *cpu_to_rapl_pmu(unsigned int cpu)
> > > -{
> > > -       unsigned int rapl_pmu_idx = get_rapl_pmu_idx(cpu);
> > > -
> > > -       /*
> > > -        * The unsigned check also catches the '-1' return value
> > > for non
> > > -        * existent mappings in the topology map.
> > > -        */
> > 
> > 
> > See the comment here why rapl_pmu_idx should be an "unsigned int".
> > 
> > 
> > > -       return rapl_pmu_idx < rapl_pmus->nr_rapl_pmu ? rapl_pmus-
> > > >pmus[rapl_pmu_idx] : NULL;
> > > -}
> > > -
> > >  static inline u64 rapl_read_counter(struct perf_event *event)
> > >  {
> > >         u64 raw;
> > > @@ -348,7 +337,7 @@ static void rapl_pmu_event_del(struct
> > > perf_event *event, int flags)
> > >  static int rapl_pmu_event_init(struct perf_event *event)
> > >  {
> > >         u64 cfg = event->attr.config & RAPL_EVENT_MASK;
> > > -       int bit, ret = 0;
> > > +       int bit, rapl_pmu_idx, ret = 0;
> > 
> > Considering that, shouldn't rapl_pmu_idx be an "unsigned int" no?
> 
> Correct, with unsigned int we will be able to check for negative
> values as well with the 
> "if (rapl_pmu_idx >= rapl_pmus->nr_rapl_pmu)" check. Will fix this in
> next version.
> 
you can stick with unsigned int here, but in patch 10/10, IMO, making
get_rapl_pmu_idx() return int instead of unsigned int is more
straightforward.

thanks,
rui

> Thanks,
> Dhananjay
> 
> > 
> > --
> > Thanks and Regards
> > gautham.
> > 
> > 
> > >         struct rapl_pmu *pmu;
> > >  
> > >         /* only look at RAPL events */
> > > @@ -376,8 +365,12 @@ static int rapl_pmu_event_init(struct
> > > perf_event *event)
> > >         if (event->attr.sample_period) /* no sampling */
> > >                 return -EINVAL;
> > >  
> > > +       rapl_pmu_idx = get_rapl_pmu_idx(event->cpu);
> > > +       if (rapl_pmu_idx >= rapl_pmus->nr_rapl_pmu)
> > > +               return -EINVAL;
> > > +
> > >         /* must be done before validate_group */
> > > -       pmu = cpu_to_rapl_pmu(event->cpu);
> > > +       pmu = rapl_pmus->pmus[rapl_pmu_idx];
> > >         if (!pmu)
> > >                 return -EINVAL;
> > >         event->pmu_private = pmu;
> > > -- 
> > > 2.34.1
> > >