On Mon, Oct 26, 2015 at 11:37:23AM +0800, Huang Rui wrote:
> On Fri, Oct 23, 2015 at 06:59:19AM -0700, Guenter Roeck wrote:
> > On 10/19/2015 07:28 PM, Huang Rui wrote:
> > >PTSC is the performance timestamp counter value in a cpu core and the
> > >cores in one compute unit have the fixed frequency. So it picks up the
> > >performance timestamp counter value of the first core per compute unit
> > >to measure the interval for average power per compute unit.
> > >
> > >Signed-off-by: Huang Rui <[email protected]>
> > >Cc: Borislav Petkov <[email protected]>
> > >Cc: Guenter Roeck <[email protected]>
> > >Cc: Peter Zijlstra <[email protected]>
> > >Cc: Ingo Molnar <[email protected]>
> > >---
> > > arch/x86/include/asm/msr-index.h | 1 +
> > > drivers/hwmon/fam15h_power.c | 5 +++++
> > > 2 files changed, 6 insertions(+)
...
> > >@@ -132,6 +134,9 @@ static void do_read_registers_on_cu(void *_data)
> > >
> > > WARN_ON(rdmsrl_safe(MSR_F15H_CU_PWR_ACCUMULATOR,
> > > &data->cu_acc_power[cu]));
> > >+
> > >+ WARN_ON(rdmsrl_safe(MSR_F15H_PTSC,
> > >+ &data->cpu_sw_pwr_ptsc[cu]));
> > > }
> >
> > I am not really happy with those WARN_ON, or even an error message.
> > If the error is seen, it may be persistent.
> >
> > If an error check is really needed here, it might make more sense to store
> > the read error and return it to user space if the respective sysfs attribute
> > is read.
> >
>
> I am OK with removing WARN_ON here. Boris, if you also agree with it,
The real question should be: are those MSR accesses behind a CPUID flag check
which guarantees their existence?
If so, you don't really need WARN_ONs. And the MSR accesses better be
behind a CPUID flag anyway because reading non-existent MSRs is pretty
much pure waste of energy.
--
Regards/Gruss,
Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284
(AG Nürnberg)
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