| Message ID | 20210503192810.36084-3-jandryuk@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Intel Hardware P-States (HWP) support | expand |
On 03.05.2021 21:27, Jason Andryuk wrote: > acpi-cpufreq scales the aperf/mperf measurements by max_freq, but HWP > needs to scale by base frequency. Settings max_freq to base_freq > "works" but the code is not obvious, and returning values to userspace > is tricky. Add an additonal perf_freq member which is used for scaling > aperf/mperf measurements. > > Signed-off-by: Jason Andryuk <jandryuk@gmail.com> > --- > I don't like this, but it seems the best way to re-use the common > aperf/mperf code. The other option would be to add wrappers that then > do the acpi vs. hwp scaling. Not sure I understand what you mean by "wrappers". I would assume that for hwp you simply install a different getavg hook? Or else I guess I'd need to see at least an outline of what you see as the alternative. Jan
On Wed, May 26, 2021 at 9:24 AM Jan Beulich <jbeulich@suse.com> wrote: > > On 03.05.2021 21:27, Jason Andryuk wrote: > > acpi-cpufreq scales the aperf/mperf measurements by max_freq, but HWP > > needs to scale by base frequency. Settings max_freq to base_freq > > "works" but the code is not obvious, and returning values to userspace > > is tricky. Add an additonal perf_freq member which is used for scaling > > aperf/mperf measurements. > > > > Signed-off-by: Jason Andryuk <jandryuk@gmail.com> > > --- > > I don't like this, but it seems the best way to re-use the common > > aperf/mperf code. The other option would be to add wrappers that then > > do the acpi vs. hwp scaling. > > Not sure I understand what you mean by "wrappers". I would assume that > for hwp you simply install a different getavg hook? Or else I guess > I'd need to see at least an outline of what you see as the alternative. Something like a common get_measured_perf() returning just the aperf/mperf ratio with cpufreq_driver specific getavg() scaling as appropriate. Regards, Jason
diff --git a/xen/arch/x86/acpi/cpufreq/cpufreq.c b/xen/arch/x86/acpi/cpufreq/cpufreq.c index f1f3c6923f..5eac2f7321 100644 --- a/xen/arch/x86/acpi/cpufreq/cpufreq.c +++ b/xen/arch/x86/acpi/cpufreq/cpufreq.c @@ -317,7 +317,7 @@ unsigned int get_measured_perf(unsigned int cpu, unsigned int flag) else perf_percent = 0; - return policy->cpuinfo.max_freq * perf_percent / 100; + return policy->cpuinfo.perf_freq * perf_percent / 100; } static unsigned int get_cur_freq_on_cpu(unsigned int cpu) diff --git a/xen/drivers/cpufreq/utility.c b/xen/drivers/cpufreq/utility.c index b93895d4dd..788929e079 100644 --- a/xen/drivers/cpufreq/utility.c +++ b/xen/drivers/cpufreq/utility.c @@ -236,6 +236,7 @@ int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy, policy->min = policy->cpuinfo.min_freq = min_freq; policy->max = policy->cpuinfo.max_freq = max_freq; + policy->cpuinfo.perf_freq = max_freq; policy->cpuinfo.second_max_freq = second_max_freq; if (policy->min == ~0) diff --git a/xen/include/acpi/cpufreq/cpufreq.h b/xen/include/acpi/cpufreq/cpufreq.h index 56df5eebed..b91859ce5d 100644 --- a/xen/include/acpi/cpufreq/cpufreq.h +++ b/xen/include/acpi/cpufreq/cpufreq.h @@ -37,6 +37,9 @@ extern struct acpi_cpufreq_data *cpufreq_drv_data[NR_CPUS]; struct cpufreq_cpuinfo { unsigned int max_freq; unsigned int second_max_freq; /* P1 if Turbo Mode is on */ + unsigned int perf_freq; /* Scaling freq for aperf/mpref. + acpi-cpufreq uses max_freq, but HWP uses + base_freq.*/ unsigned int min_freq; unsigned int transition_latency; /* in 10^(-9) s = nanoseconds */ };
acpi-cpufreq scales the aperf/mperf measurements by max_freq, but HWP needs to scale by base frequency. Settings max_freq to base_freq "works" but the code is not obvious, and returning values to userspace is tricky. Add an additonal perf_freq member which is used for scaling aperf/mperf measurements. Signed-off-by: Jason Andryuk <jandryuk@gmail.com> --- I don't like this, but it seems the best way to re-use the common aperf/mperf code. The other option would be to add wrappers that then do the acpi vs. hwp scaling. --- xen/arch/x86/acpi/cpufreq/cpufreq.c | 2 +- xen/drivers/cpufreq/utility.c | 1 + xen/include/acpi/cpufreq/cpufreq.h | 3 +++ 3 files changed, 5 insertions(+), 1 deletion(-)