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Subject[RFC/RFT] [PATCH 08/10] cpufreq: intel_pstate: Dyanmically update busy pct
Date
Calculate hwp_boost_threshold_busy_pct (task busy percent, which is
worth boosting) and hwp_boost_pstate_threshold (Don't boost if
CPU already has some performance) based on platform, min, max and
turbo frequencies.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
---
drivers/cpufreq/intel_pstate.c | 40 +++++++++++++++++++++++++++++++++++++++-
1 file changed, 39 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index ec455af..c43edce 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -1463,6 +1463,42 @@ static inline int intel_pstate_get_sched_util(struct cpudata *cpu)
return util * 100 / max;
}

+
+static inline void intel_pstate_update_busy_threshold(struct cpudata *cpu)
+{
+ if (!hwp_boost_threshold_busy_pct) {
+ int min_freq, max_freq;
+
+ min_freq = cpu->pstate.min_pstate * cpu->pstate.scaling;
+ update_turbo_state();
+ max_freq = global.turbo_disabled || global.no_turbo ?
+ cpu->pstate.max_freq : cpu->pstate.turbo_freq;
+
+ /*
+ * We are guranteed to get atleast min P-state. If we assume
+ * P-state is proportional to load (such that 10% load
+ * increase will result in 10% P-state increase), we will
+ * get at least min P-state till we have atleast
+ * (min * 100/max) percent cpu load. So any load less than
+ * than this this we shouldn't do any boost. Then boosting
+ * is not free, we will add atleast 20% offset.
+ */
+ hwp_boost_threshold_busy_pct = min_freq * 100 / max_freq;
+ hwp_boost_threshold_busy_pct += 20;
+ pr_debug("hwp_boost_threshold_busy_pct = %d\n",
+ hwp_boost_threshold_busy_pct);
+ }
+
+ /* P1 percent out of total range of P-states */
+ if (cpu->pstate.max_freq != cpu->pstate.turbo_freq) {
+ hwp_boost_pstate_threshold =
+ cpu->pstate.max_freq * SCHED_CAPACITY_SCALE / cpu->pstate.turbo_freq;
+ pr_debug("hwp_boost_pstate_threshold = %d\n",
+ hwp_boost_pstate_threshold);
+ }
+
+}
+
static inline void intel_pstate_update_util_hwp(struct update_util_data *data,
u64 time, unsigned int flags)
{
@@ -2061,8 +2097,10 @@ static int __intel_pstate_cpu_init(struct cpufreq_policy *policy)

policy->fast_switch_possible = true;

- if (hwp_active)
+ if (hwp_active) {
csd_init(cpu);
+ intel_pstate_update_busy_threshold(cpu);
+ }

return 0;
}
--
2.9.5
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