On Wed, Oct 25, 2023 at 08:27:23PM +0530, Sumit Gupta wrote: > > > > > [adding Ionela] > > > > On Wed, Oct 25, 2023 at 05:38:46PM +0800, Zeng Heng wrote: > > > As ARM AMU's document says, all counters are subject to any changes > > > in clock frequency, including clock stopping caused by the WFI and WFE > > > instructions. > > > > > > Therefore, using smp_call_on_cpu() to trigger target CPU to > > > read self's AMU counters, which ensures the counters are working > > > properly while cstate feature is enabled. > > > > IIUC there's a pretty deliberate split with all the actual reading of the AMU > > living in arch/arm64/kernel/topolgy.c, and the driver code being (relatively) > > generic. > > > > We already have code in arch/arm64/kernel/topolgy.c to read counters on a > > specific CPU; why can't e reuse that (and avoid exporting cpu_has_amu_feat())? > > > This patch seems mostly based on my previous patch [1] and discussed here > [2] already. Beata [CCed] shared an alternate approach [3] leveraging > existing code from 'topology.c' to get the average freq for last tick > period. > > > Beata, > > Could you share v2 of [3] with the request to merge. We can try to solve the > issue with CPU IDLE case later on top? > Will do (same for the below request if feasible) --- BR B. > Additionally, also please include the fix in [4] if it looks fine. > > Best Regards, > Sumit Gupta > > [1] https://lore.kernel.org/all/20230418113459.12860-7-sumitg@xxxxxxxxxx/ > [2] https://lore.kernel.org/lkml/cde1d8a9-3a21-e82b-7895-40603a14d898@xxxxxxxxxx/T/#m2174305de4706006e0bd9c103a0e5ff61cea7a12 > [3] > https://lore.kernel.org/lkml/20230606155754.245998-1-beata.michalska@xxxxxxx/ > [4] > https://lore.kernel.org/lkml/6a5710f6-bfbb-5dfd-11cd-0cd02220cee7@xxxxxxxxxx/ > > > > > > > > Reported-by: Sumit Gupta <sumitg@xxxxxxxxxx> > > > Link: https://lore.kernel.org/all/20230418113459.12860-7-sumitg@xxxxxxxxxx/ > > > Signed-off-by: Zeng Heng <zengheng4@xxxxxxxxxx> > > > --- > > > drivers/cpufreq/cppc_cpufreq.c | 39 ++++++++++++++++++++++++++-------- > > > 1 file changed, 30 insertions(+), 9 deletions(-) > > > > > > diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c > > > index fe08ca419b3d..321a9dc9484d 100644 > > > --- a/drivers/cpufreq/cppc_cpufreq.c > > > +++ b/drivers/cpufreq/cppc_cpufreq.c > > > @@ -90,6 +90,12 @@ static int cppc_perf_from_fbctrs(struct cppc_cpudata *cpu_data, > > > struct cppc_perf_fb_ctrs *fb_ctrs_t0, > > > struct cppc_perf_fb_ctrs *fb_ctrs_t1); > > > > > > +struct fb_ctr_pair { > > > + u32 cpu; > > > + struct cppc_perf_fb_ctrs fb_ctrs_t0; > > > + struct cppc_perf_fb_ctrs fb_ctrs_t1; > > > +}; > > > + > > > /** > > > * cppc_scale_freq_workfn - CPPC arch_freq_scale updater for frequency invariance > > > * @work: The work item. > > > @@ -840,9 +846,24 @@ static int cppc_perf_from_fbctrs(struct cppc_cpudata *cpu_data, > > > return (reference_perf * delta_delivered) / delta_reference; > > > } > > > > > > +static int cppc_get_perf_ctrs_pair(void *val) > > > +{ > > > + struct fb_ctr_pair *fb_ctrs = val; > > > + int cpu = fb_ctrs->cpu; > > > + int ret; > > > + > > > + ret = cppc_get_perf_ctrs(cpu, &fb_ctrs->fb_ctrs_t0); > > > + if (ret) > > > + return ret; > > > + > > > + udelay(2); /* 2usec delay between sampling */ > > > + > > > + return cppc_get_perf_ctrs(cpu, &fb_ctrs->fb_ctrs_t1); > > > +} > > > + > > > static unsigned int cppc_cpufreq_get_rate(unsigned int cpu) > > > { > > > - struct cppc_perf_fb_ctrs fb_ctrs_t0 = {0}, fb_ctrs_t1 = {0}; > > > + struct fb_ctr_pair fb_ctrs = { .cpu = cpu, }; > > > struct cpufreq_policy *policy = cpufreq_cpu_get(cpu); > > > struct cppc_cpudata *cpu_data = policy->driver_data; > > > u64 delivered_perf; > > > @@ -850,18 +871,18 @@ static unsigned int cppc_cpufreq_get_rate(unsigned int cpu) > > > > > > cpufreq_cpu_put(policy); > > > > > > - ret = cppc_get_perf_ctrs(cpu, &fb_ctrs_t0); > > > - if (ret) > > > - return 0; > > > - > > > - udelay(2); /* 2usec delay between sampling */ > > > + if (cpu_has_amu_feat(cpu)) > > > + ret = smp_call_on_cpu(cpu, cppc_get_perf_ctrs_pair, > > > + &fb_ctrs, false); > > > + else > > > + ret = cppc_get_perf_ctrs_pair(&fb_ctrs); > > > > > > - ret = cppc_get_perf_ctrs(cpu, &fb_ctrs_t1); > > > if (ret) > > > return 0; > > > > > > - delivered_perf = cppc_perf_from_fbctrs(cpu_data, &fb_ctrs_t0, > > > - &fb_ctrs_t1); > > > + delivered_perf = cppc_perf_from_fbctrs(cpu_data, > > > + &fb_ctrs.fb_ctrs_t0, > > > + &fb_ctrs.fb_ctrs_t1); > > > > > > return cppc_cpufreq_perf_to_khz(cpu_data, delivered_perf); > > > } > > > -- > > > 2.25.1 > > >
