Messages in this thread Patch in this message | | | From | Joel Fernandes <> | Subject | [PATCH v2 2/2] sched: Make iowait_boost optional in schedutil | Date | Thu, 18 May 2017 23:23:44 -0700 |
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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
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