On Wed, 25 Oct 2023 at 13:55, Peter Zijlstra [off-list ref] wrote:

On Wed, Oct 18, 2023 at 06:25:38PM +0200, Vincent Guittot wrote:

quoted

The last item of a performance domain is not always the performance point
that has been used to compute CPU's capacity. This can lead to different
target frequency compared with other part of the system like schedutil and
would result in wrong energy estimation.

A new arch_scale_freq_ref() is available to return a fixed and coherent
frequency reference that can be used when computing the CPU's frequency
for an level of utilization. Use this function to get this reference
frequency.

Energy model is never used without defining arch_scale_freq_ref() but
can be compiled. Define a default arch_scale_freq_ref() returning 0
in such case.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Tested-by: Lukasz Luba <lukasz.luba@arm.com>

---
 include/linux/energy_model.h | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h
index b9caa01dfac4..1b0c8490d4bd 100644
--- a/include/linux/energy_model.h
+++ b/include/linux/energy_model.h

@@ -204,6 +204,14 @@ struct em_perf_state *em_pd_get_efficient_state(struct em_perf_domain *pd,
      return ps;
 }

+#ifndef arch_scale_freq_ref
+static __always_inline
+unsigned int arch_scale_freq_ref(int cpu)
+{
+     return 0;
+}
+#endif

Hmm, did I not see the exact same thing in cpufreq.h two patches ago?

Probably, this has been added because of error returned by some
allyes/randconfig on x86

_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel