On Thu, 2021-12-09 at 17:57 +0100, Daniel Lezcano wrote:

On 09/12/2021 17:03, Ricardo Neri wrote:

quoted

On Tue, Nov 30, 2021 at 10:29:46AM +0100, Daniel Lezcano wrote:

quoted

On 06/11/2021 02:33, Ricardo Neri wrote:

quoted

From: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>

Add a new netlink event to notify change in CPU capabilities in
terms of
performance and efficiency.

Firmware may change CPU capabilities as a result of thermal
events in the
system or to account for changes in the TDP (thermal design
power) level.

This notification type will allow user space to avoid running
workloads
on certain CPUs or proactively adjust power limits to avoid
future events.

[ ... ]

quoted

+       [THERMAL_GENL_ATTR_CPU_CAPABILITY_ID]   = { .type =
NLA_U32 },
+       [THERMAL_GENL_ATTR_CPU_CAPABILITY_PERF] = { .type =
NLA_U32 },
+       [THERMAL_GENL_ATTR_CPU_CAPABILITY_EFF]  = { .type =
NLA_U32 },
 };

AFAIU, 0 <= perf < 256 and 0 <= eff < 256, right?

Is the following true?

        0 <= perf + eff < 256

No, they are not. They are set independently.

I understand they can be set independently but is the constraint
above
correct? For example, can the system send perf=255 and eff=255 or
perf=0
and eff=0 ?

perf = 0 and eff = 0 is already the case in the current processors.
Both FF is not the case as the current generation use real performance
which can't be FF. Also it is unlikely that at max performance you have
max efficiency.

Thanks,
Srinivas

May be I misunderstood but I was expecting at least some kind of
connection between perf and eff (when eff is high, perf is low and
the
opposite).