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Message-ID: <c961bae053da7287bfce49b2c1c2e7e6c754710a.camel@linux.intel.com>
Date: Mon, 22 Jan 2024 03:35:27 -0800
From: srinivas pandruvada <srinivas.pandruvada@...ux.intel.com>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>, rafael@...nel.org,
viresh.kumar@...aro.org
Cc: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] cpufreq: intel_pstate: Directly use stored ratios for
max frequencies
On Mon, 2024-01-22 at 11:53 +0100, Rafael J. Wysocki wrote:
> On Thursday, January 18, 2024 1:05:13 PM CET Srinivas Pandruvada
> wrote:
> > Avoid unnecessary calculation for converting frequency to
> > performance
> > ratio by using a scaling factor for the maximum non turbo and turbo
>
[...]
> ---
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> Subject: [PATCH v1] cpufreq: intel_pstate: Refine computation of P-
> state for given frequency
>
> On systems using HWP, if a given frequency is equal to the maximum
> turbo
> frequency or the maximum non-turbo frequency, the HWP performance
> level
> corresponding to it is already known and can be used directly without
> any computation.
>
> Accordingly, adjust the code to use the known HWP performance levels
> in
> the cases mentioned above.
>
> This also helps to avoid limiting CPU capacity artificially in some
> cases when the BIOS produces the HWP_CAP numbers using a different
> E-core-to-P-core performance scaling factor than expected by the
> kernel.
>
> Fixes: f5c8cf2a4992 ("cpufreq: intel_pstate: hybrid: Use known
> scaling factor for P-cores")
> Cc: 6.1+ <stable@...r.kernel.org> # 6.1+
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
Tested on the system which showed the issue, this patch work fine.
Thanks,
Srinivas
> drivers/cpufreq/intel_pstate.c | 55 +++++++++++++++++++++++++-----
> -----------
> 1 file changed, 34 insertions(+), 21 deletions(-)
>
> Index: linux-pm/drivers/cpufreq/intel_pstate.c
> ===================================================================
> --- linux-pm.orig/drivers/cpufreq/intel_pstate.c
> +++ linux-pm/drivers/cpufreq/intel_pstate.c
> @@ -529,6 +529,30 @@ static int intel_pstate_cppc_get_scaling
> }
> #endif /* CONFIG_ACPI_CPPC_LIB */
>
> +static int intel_pstate_freq_to_hwp_rel(struct cpudata *cpu, int
> freq,
> + unsigned int relation)
> +{
> + if (freq == cpu->pstate.turbo_freq)
> + return cpu->pstate.turbo_pstate;
> +
> + if (freq == cpu->pstate.max_freq)
> + return cpu->pstate.max_pstate;
> +
> + switch (relation) {
> + case CPUFREQ_RELATION_H:
> + return freq / cpu->pstate.scaling;
> + case CPUFREQ_RELATION_C:
> + return DIV_ROUND_CLOSEST(freq, cpu->pstate.scaling);
> + }
> +
> + return DIV_ROUND_UP(freq, cpu->pstate.scaling);
> +}
> +
> +static int intel_pstate_freq_to_hwp(struct cpudata *cpu, int freq)
> +{
> + return intel_pstate_freq_to_hwp_rel(cpu, freq,
> CPUFREQ_RELATION_L);
> +}
> +
> /**
> * intel_pstate_hybrid_hwp_adjust - Calibrate HWP performance
> levels.
> * @cpu: Target CPU.
> @@ -546,6 +570,7 @@ static void intel_pstate_hybrid_hwp_adju
> int perf_ctl_scaling = cpu->pstate.perf_ctl_scaling;
> int perf_ctl_turbo = pstate_funcs.get_turbo(cpu->cpu);
> int scaling = cpu->pstate.scaling;
> + int freq;
>
> pr_debug("CPU%d: perf_ctl_max_phys = %d\n", cpu->cpu,
> perf_ctl_max_phys);
> pr_debug("CPU%d: perf_ctl_turbo = %d\n", cpu->cpu,
> perf_ctl_turbo);
> @@ -559,16 +584,16 @@ static void intel_pstate_hybrid_hwp_adju
> cpu->pstate.max_freq = rounddown(cpu->pstate.max_pstate *
> scaling,
> perf_ctl_scaling);
>
> - cpu->pstate.max_pstate_physical =
> - DIV_ROUND_UP(perf_ctl_max_phys *
> perf_ctl_scaling,
> - scaling);
> + freq = perf_ctl_max_phys * perf_ctl_scaling;
> + cpu->pstate.max_pstate_physical =
> intel_pstate_freq_to_hwp(cpu, freq);
>
> - cpu->pstate.min_freq = cpu->pstate.min_pstate *
> perf_ctl_scaling;
> + freq = cpu->pstate.min_pstate * perf_ctl_scaling;
> + cpu->pstate.min_freq = freq;
> /*
> * Cast the min P-state value retrieved via
> pstate_funcs.get_min() to
> * the effective range of HWP performance levels.
> */
> - cpu->pstate.min_pstate = DIV_ROUND_UP(cpu->pstate.min_freq,
> scaling);
> + cpu->pstate.min_pstate = intel_pstate_freq_to_hwp(cpu, freq);
> }
>
> static inline void update_turbo_state(void)
> @@ -2528,13 +2553,12 @@ static void intel_pstate_update_perf_lim
> * abstract values to represent performance rather than pure
> ratios.
> */
> if (hwp_active && cpu->pstate.scaling != perf_ctl_scaling) {
> - int scaling = cpu->pstate.scaling;
> int freq;
>
> freq = max_policy_perf * perf_ctl_scaling;
> - max_policy_perf = DIV_ROUND_UP(freq, scaling);
> + max_policy_perf = intel_pstate_freq_to_hwp(cpu,
> freq);
> freq = min_policy_perf * perf_ctl_scaling;
> - min_policy_perf = DIV_ROUND_UP(freq, scaling);
> + min_policy_perf = intel_pstate_freq_to_hwp(cpu,
> freq);
> }
>
> pr_debug("cpu:%d min_policy_perf:%d max_policy_perf:%d\n",
> @@ -2908,18 +2932,7 @@ static int intel_cpufreq_target(struct c
>
> cpufreq_freq_transition_begin(policy, &freqs);
>
> - switch (relation) {
> - case CPUFREQ_RELATION_L:
> - target_pstate = DIV_ROUND_UP(freqs.new, cpu-
> >pstate.scaling);
> - break;
> - case CPUFREQ_RELATION_H:
> - target_pstate = freqs.new / cpu->pstate.scaling;
> - break;
> - default:
> - target_pstate = DIV_ROUND_CLOSEST(freqs.new, cpu-
> >pstate.scaling);
> - break;
> - }
> -
> + target_pstate = intel_pstate_freq_to_hwp_rel(cpu, freqs.new,
> relation);
> target_pstate = intel_cpufreq_update_pstate(policy,
> target_pstate, false);
>
> freqs.new = target_pstate * cpu->pstate.scaling;
> @@ -2937,7 +2950,7 @@ static unsigned int intel_cpufreq_fast_s
>
> update_turbo_state();
>
> - target_pstate = DIV_ROUND_UP(target_freq, cpu-
> >pstate.scaling);
> + target_pstate = intel_pstate_freq_to_hwp(cpu, target_freq);
>
> target_pstate = intel_cpufreq_update_pstate(policy,
> target_pstate, true);
>
>
>
>
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