Re: [PATCH v2 05/10] hwmon: (fam15h_power) Add compute unit accumulated power

[Guenter Roeck]

On 10/23/2015 06:27 AM, Borislav Petkov wrote:
> On Tue, Oct 20, 2015 at 10:28:24AM +0800, Huang Rui wrote:
> > This patch adds a member in fam15h_power_data which specifies the
> > compute unit accumulated power. It adds do_read_registers_on_cu to do
> > all the read to all MSRs and run it on one of the online cores on each
> > compute unit with smp_call_function_many(). This behavior can decrease
> > IPI numbers.
> >
> > Suggested-by: Borislav Petkov <bp@xxxxxxxxx>
> > Signed-off-by: Huang Rui <ray.huang@xxxxxxx>
> > Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
> > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> > Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> > ---
> >   drivers/hwmon/fam15h_power.c | 68 +++++++++++++++++++++++++++++++++++++++++++-
> >   1 file changed, 67 insertions(+), 1 deletion(-)

[ ... ]

> > +static void do_read_registers_on_cu(void *_data)
> > +{
> > +	struct fam15h_power_data *data = _data;
> > +	int cpu, cu, cores_per_cu;
> > +
> > +	cpu = smp_processor_id();
> > +
> > +	cores_per_cu = amd_get_cores_per_cu();
> > +	cu = cpu / cores_per_cu;
> > +
> > +	WARN_ON(rdmsrl_safe(MSR_F15H_CU_PWR_ACCUMULATOR,
> > +			    &data->cu_acc_power[cu]));
>
> I guess the WARN_ON's here should be WARN_ON_ONCE() - otherwise dmesg is
> filling up very quickly.
I don't really understand why WARN_ON (or WARN_ON_ONCE)
would be warranted here in the first place.

Guenter

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