lkml.org 
[lkml]   [2017]   [May]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v2 2/2] sched: Make iowait_boost optional in schedutil
Date
We should apply the iowait boost only if cpufreq policy has iowait boost
enabled. Also make it a schedutil configuration from sysfs so it can be turned
on/off if needed (by default initialize it to the policy value).

For systems that don't need/want it enabled, such as those on arm64 based
mobile devices that are battery operated, it saves energy when the cpufreq
driver policy doesn't have it enabled (details below):

Here are some results for energy measurements collected running a YouTube video
for 30 seconds:
Before: 8.042533 mWh
After: 7.948377 mWh
Energy savings is ~1.2%

Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Joel Fernandes <joelaf@google.com>
---
kernel/sched/cpufreq_schedutil.c | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)

diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index 76877a62b5fa..0e392b58b9b3 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -24,6 +24,7 @@
struct sugov_tunables {
struct gov_attr_set attr_set;
unsigned int rate_limit_us;
+ bool iowait_boost_enable;
};

struct sugov_policy {
@@ -171,6 +172,11 @@ static void sugov_get_util(unsigned long *util, unsigned long *max)
static void sugov_set_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
unsigned int flags)
{
+ struct sugov_policy *sg_policy = sg_cpu->sg_policy;
+
+ if (!sg_policy->tunables->iowait_boost_enable)
+ return;
+
if (flags & SCHED_CPUFREQ_IOWAIT) {
sg_cpu->iowait_boost = sg_cpu->iowait_boost_max;
} else if (sg_cpu->iowait_boost) {
@@ -386,10 +392,34 @@ static ssize_t rate_limit_us_store(struct gov_attr_set *attr_set, const char *bu
return count;
}

+static ssize_t iowait_boost_enable_show(struct gov_attr_set *attr_set,
+ char *buf)
+{
+ struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
+
+ return sprintf(buf, "%u\n", tunables->iowait_boost_enable);
+}
+
+static ssize_t iowait_boost_enable_store(struct gov_attr_set *attr_set,
+ const char *buf, size_t count)
+{
+ struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
+ bool enable;
+
+ if (kstrtobool(buf, &enable))
+ return -EINVAL;
+
+ tunables->iowait_boost_enable = enable;
+
+ return count;
+}
+
static struct governor_attr rate_limit_us = __ATTR_RW(rate_limit_us);
+static struct governor_attr iowait_boost_enable = __ATTR_RW(iowait_boost_enable);

static struct attribute *sugov_attributes[] = {
&rate_limit_us.attr,
+ &iowait_boost_enable.attr,
NULL
};

@@ -543,6 +573,8 @@ static int sugov_init(struct cpufreq_policy *policy)
tunables->rate_limit_us *= lat;
}

+ tunables->iowait_boost_enable = policy->iowait_boost_enable;
+
policy->governor_data = sg_policy;
sg_policy->tunables = tunables;

--
2.13.0.303.g4ebf302169-goog
\
 
 \ /
  Last update: 2017-05-19 08:24    [W:0.146 / U:0.192 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site