Introduce op for ondemand governor that is used to map load to
frequency. It allows a cpufreq driver to provide a specific mapping
function if the generic function is not optimal for the driver.
Performance results (kernel compile with different number of jobs)
based on 4.8.0-rc7 (with and w/o my patches on top) from
an HP ProLiant DL580 Gen8 system using pcc-cpufreq:
- Intel(R) Xeon(R) CPU E7-4890 v2 @ 2.80GHz
- 60 CPUs, 128GB RAM
vanilla generic_map_load_to_freq function
# of jobs user sys elapsed % CPU user sys elapsed % CPU
2 445.44 110.51 272.99 203.00 445.56 111.22 273.35 203.00
4 444.41 126.20 142.81 399.00 445.61 126.10 143.12 399.00
8 483.04 150.58 82.19 770.40 483.51 150.84 82.17 771.40
16 626.81 185.01 55.00 1475.40 628.01 185.54 55.02 1477.80
32 816.72 204.39 37.26 2740.00 818.58 205.51 37.02 2765.40
64 406.59 51.12 14.04 3257.80 406.22 51.84 13.84 3308.80
120 413.00 48.39 14.36 3211.20 413.61 49.06 14.54 3181.00
Similar tests on another system using acpi_cpufreq didn't show
significant performance differences between these two kernel versions.
Link: https://marc.info/?i=20160819121814.GA17296%40suselix.suse.de
Signed-off-by: Andreas Herrmann <aherrm...@suse.com>
---
drivers/cpufreq/cpufreq_governor.h | 5 +++++
drivers/cpufreq/cpufreq_ondemand.c | 35 ++++++++++++++++++++++++++++++-----
2 files changed, 35 insertions(+), 5 deletions(-)
diff --git a/drivers/cpufreq/cpufreq_governor.h
b/drivers/cpufreq/cpufreq_governor.h
index ef1037e..9fef947 100644
--- a/drivers/cpufreq/cpufreq_governor.h
+++ b/drivers/cpufreq/cpufreq_governor.h
@@ -171,6 +171,8 @@ void cpufreq_dbs_governor_limits(struct cpufreq_policy
*policy);
struct od_ops {
unsigned int (*powersave_bias_target)(struct cpufreq_policy *policy,
unsigned int freq_next, unsigned int relation);
+ unsigned int (*map_load_to_freq)(struct cpufreq_policy *policy,
+ unsigned int load);
};
unsigned int dbs_update(struct cpufreq_policy *policy);
@@ -178,6 +180,9 @@ void od_register_powersave_bias_handler(unsigned int (*f)
(struct cpufreq_policy *, unsigned int, unsigned int),
unsigned int powersave_bias);
void od_unregister_powersave_bias_handler(void);
+void od_register_map_load_to_freq_handler(unsigned int (*f)
+ (struct cpufreq_policy *, unsigned int));
+void od_unregister_map_load_to_freq_handler(void);
ssize_t store_sampling_rate(struct gov_attr_set *attr_set, const char *buf,
size_t count);
void gov_update_cpu_data(struct dbs_data *dbs_data);
diff --git a/drivers/cpufreq/cpufreq_ondemand.c
b/drivers/cpufreq/cpufreq_ondemand.c
index 3a1f49f..d245f1c 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -112,6 +112,20 @@ static void ondemand_powersave_bias_init(struct
cpufreq_policy *policy)
dbs_info->freq_lo = 0;
}
+/*
+ * Calculate the next frequency proportional to load
+ */
+static unsigned int generic_map_load_to_freq(struct cpufreq_policy *policy,
+ unsigned int load)
+{
+ unsigned int min_f, max_f;
+
+ min_f = policy->cpuinfo.min_freq;
+ max_f = policy->cpuinfo.max_freq;
+
+ return (min_f + load * (max_f - min_f) / 100);
+}
+
static void dbs_freq_increase(struct cpufreq_policy *policy, unsigned int freq)
{
struct policy_dbs_info *policy_dbs = policy->governor_data;
@@ -150,12 +164,9 @@ static void od_update(struct cpufreq_policy *policy)
policy_dbs->rate_mult = dbs_data->sampling_down_factor;
dbs_freq_increase(policy, policy->max);
} else {
- /* Calculate the next frequency proportional to load */
- unsigned int freq_next, min_f, max_f;
+ unsigned int freq_next;
- min_f = policy->cpuinfo.min_freq;
- max_f = policy->cpuinfo.max_freq;
- freq_next = min_f + load * (max_f - min_f) / 100;
+ freq_next = od_ops.map_load_to_freq(policy, load);
/* No longer fully busy, reset rate_mult */
policy_dbs->rate_mult = 1;
@@ -410,6 +421,7 @@ static void od_start(struct cpufreq_policy *policy)
static struct od_ops od_ops = {
.powersave_bias_target = generic_powersave_bias_target,
+ .map_load_to_freq = generic_map_load_to_freq,
};
static struct dbs_governor od_dbs_gov = {
@@ -476,6 +488,19 @@ void od_unregister_powersave_bias_handler(void)
}
EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler);
+void od_register_map_load_to_freq_handler(unsigned int (*f)
+ (struct cpufreq_policy *, unsigned int))
+{
+ od_ops.map_load_to_freq = f;
+}
+EXPORT_SYMBOL_GPL(od_register_map_load_to_freq_handler);
+
+void od_unregister_map_load_to_freq_handler(void)
+{
+ od_ops.map_load_to_freq = generic_map_load_to_freq;
+}
+EXPORT_SYMBOL_GPL(od_unregister_map_load_to_freq_handler);
+
static int __init cpufreq_gov_dbs_init(void)
{
return cpufreq_register_governor(CPU_FREQ_GOV_ONDEMAND);
--
1.9.1
