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Date: Mon, 14 Dec 2020 19:29:18 -0800
From: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>,
Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
Viresh Kumar <viresh.kumar@...aro.org>,
Peter Zijlstra <peterz@...radead.org>,
Doug Smythies <dsmythies@...us.net>,
Giovanni Gherdovich <ggherdovich@...e.com>
Subject: Re: [PATCH v2 3/3] cpufreq: intel_pstate: Implement the
->adjust_perf() callback
On Mon, 2020-12-14 at 21:09 +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>
> Make intel_pstate expose the ->adjust_perf() callback when it
> operates in the passive mode with HWP enabled which causes the
> schedutil governor to use that callback instead of ->fast_switch().
>
> The minimum and target performance-level values passed by the
> governor to ->adjust_perf() are converted to HWP.REQ.MIN and
> HWP.REQ.DESIRED, respectively, which allows the processor to
> adjust its configuration to maximize energy-efficiency while
> providing sufficient capacity.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
> ---
>
> v1 -> v2:
> - No changes.
>
> ---
> drivers/cpufreq/intel_pstate.c | 70
> +++++++++++++++++++++++++++++++++--------
> 1 file changed, 58 insertions(+), 12 deletions(-)
>
> Index: linux-pm/drivers/cpufreq/intel_pstate.c
> ===================================================================
> --- linux-pm.orig/drivers/cpufreq/intel_pstate.c
> +++ linux-pm/drivers/cpufreq/intel_pstate.c
> @@ -2526,20 +2526,19 @@ static void intel_cpufreq_trace(struct c
> fp_toint(cpu->iowait_boost * 100));
> }
>
> -static void intel_cpufreq_adjust_hwp(struct cpudata *cpu, u32
> target_pstate,
> - bool strict, bool fast_switch)
> +static void intel_cpufreq_adjust_hwp(struct cpudata *cpu, u32 min,
> u32 max,
> + u32 desired, bool fast_switch)
> {
> u64 prev = READ_ONCE(cpu->hwp_req_cached), value = prev;
>
> value &= ~HWP_MIN_PERF(~0L);
> - value |= HWP_MIN_PERF(target_pstate);
> + value |= HWP_MIN_PERF(min);
>
> - /*
> - * The entire MSR needs to be updated in order to update the
> HWP min
> - * field in it, so opportunistically update the max too if
> needed.
> - */
> value &= ~HWP_MAX_PERF(~0L);
> - value |= HWP_MAX_PERF(strict ? target_pstate : cpu-
> >max_perf_ratio);
> + value |= HWP_MAX_PERF(max);
> +
> + value &= ~HWP_DESIRED_PERF(~0L);
> + value |= HWP_DESIRED_PERF(desired);
>
> if (value == prev)
> return;
> @@ -2569,11 +2568,15 @@ static int intel_cpufreq_update_pstate(s
> int old_pstate = cpu->pstate.current_pstate;
>
> target_pstate = intel_pstate_prepare_request(cpu,
> target_pstate);
> - if (hwp_active)
> - intel_cpufreq_adjust_hwp(cpu, target_pstate,
> - policy->strict_target,
> fast_switch);
> - else if (target_pstate != old_pstate)
> + if (hwp_active) {
> + int max_pstate = policy->strict_target ?
> + target_pstate : cpu-
> >max_perf_ratio;
> +
> + intel_cpufreq_adjust_hwp(cpu, target_pstate,
> max_pstate, 0,
> + fast_switch);
> + } else if (target_pstate != old_pstate) {
> intel_cpufreq_adjust_perf_ctl(cpu, target_pstate,
> fast_switch);
> + }
>
> cpu->pstate.current_pstate = target_pstate;
>
> @@ -2634,6 +2637,47 @@ static unsigned int intel_cpufreq_fast_s
> return target_pstate * cpu->pstate.scaling;
> }
>
> +static void intel_cpufreq_adjust_perf(unsigned int cpunum,
> + unsigned long min_perf,
> + unsigned long target_perf,
> + unsigned long capacity)
> +{
> + struct cpudata *cpu = all_cpu_data[cpunum];
> + int old_pstate = cpu->pstate.current_pstate;
> + int cap_pstate, min_pstate, max_pstate, target_pstate;
> +
> + update_turbo_state();
> + cap_pstate = global.turbo_disabled ? cpu->pstate.max_pstate :
> + cpu-
> >pstate.turbo_pstate;
> +
> + /* Optimization: Avoid unnecessary divisions. */
> +
> + target_pstate = cap_pstate;
> + if (target_perf < capacity)
> + target_pstate = DIV_ROUND_UP(cap_pstate *
> target_perf, capacity);
> +
> + min_pstate = cap_pstate;
> + if (min_perf < capacity)
> + min_pstate = DIV_ROUND_UP(cap_pstate * min_perf,
> capacity);
> +
> + if (min_pstate < cpu->pstate.min_pstate)
> + min_pstate = cpu->pstate.min_pstate;
> +
> + if (min_pstate < cpu->min_perf_ratio)
> + min_pstate = cpu->min_perf_ratio;
> +
> + max_pstate = min(cap_pstate, cpu->max_perf_ratio);
> + if (max_pstate < min_pstate)
> + max_pstate = min_pstate;
> +
> + target_pstate = clamp_t(int, target_pstate, min_pstate,
> max_pstate);
> +
> + intel_cpufreq_adjust_hwp(cpu, min_pstate, max_pstate,
> target_pstate, true);
> +
> + cpu->pstate.current_pstate = target_pstate;
> + intel_cpufreq_trace(cpu, INTEL_PSTATE_TRACE_FAST_SWITCH,
> old_pstate);
> +}
> +
> static int intel_cpufreq_cpu_init(struct cpufreq_policy *policy)
> {
> int max_state, turbo_max, min_freq, max_freq, ret;
> @@ -3032,6 +3076,8 @@ static int __init intel_pstate_init(void
> intel_pstate.attr = hwp_cpufreq_attrs;
> intel_cpufreq.attr = hwp_cpufreq_attrs;
> intel_cpufreq.flags |=
> CPUFREQ_NEED_UPDATE_LIMITS;
> + intel_cpufreq.fast_switch = NULL;
> + intel_cpufreq.adjust_perf =
> intel_cpufreq_adjust_perf;
> if (!default_driver)
> default_driver = &intel_pstate;
>
>
>
>
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