The CPU usage signal is used by the scheduler as an estimation of the
overall bandwidth currently allocated on a CPU. When SchedDVFS is in
use, this signal affects the selection of the operating points (OPP)
required to accommodate all the workload allocated in a CPU.
A convenient way to boost the performance of tasks running on a CPU,
which is also little intrusive, is to boost the CPU usage signal each
time it is used to select an OPP.
This patch introduces a new function:
get_boosted_cpu_usage(cpu)
to return a boosted value for the usage of a specified CPU.
The margin added to the original usage is:
1. computed based on the "boosting strategy" in use
2. proportional to the system-wide boost value defined by provided
user-space interface
The boosted signal is used by SchedDVFS (transparently) each time it
requires to get an estimation of the capacity required for a CPU.
cc: Ingo Molnar <mi...@redhat.com>
cc: Peter Zijlstra <pet...@infradead.org>
Signed-off-by: Patrick Bellasi <patrick.bell...@arm.com>
---
kernel/sched/fair.c | 32 +++++++++++++++++++++++++++++++-
1 file changed, 31 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 15fde75..633fcab4 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4083,6 +4083,7 @@ static inline void hrtick_update(struct rq *rq)
static unsigned int capacity_margin = 1280;
static unsigned long capacity_orig_of(int cpu);
static int cpu_util(int cpu);
+static inline unsigned long boosted_cpu_util(int cpu);
static void update_capacity_of(int cpu)
{
@@ -4091,7 +4092,8 @@ static void update_capacity_of(int cpu)
if (!sched_energy_freq())
return;
- req_cap = cpu_util(cpu) * capacity_margin / capacity_orig_of(cpu);
+ req_cap = boosted_cpu_util(cpu);
+ req_cap = req_cap * capacity_margin / capacity_orig_of(cpu);
cpufreq_sched_set_cap(cpu, req_cap);
}
@@ -4766,8 +4768,36 @@ schedtune_margin(unsigned long signal, unsigned long
boost)
return margin;
}
+static inline unsigned int
+schedtune_cpu_margin(unsigned long util)
+{
+ unsigned int boost = get_sysctl_sched_cfs_boost();
+
+ if (boost == 0)
+ return 0;
+
+ return schedtune_margin(util, boost);
+}
+
+#else /* CONFIG_SCHED_TUNE */
+
+static inline unsigned int
+schedtune_cpu_margin(unsigned long util)
+{
+ return 0;
+}
+
#endif /* CONFIG_SCHED_TUNE */
+static inline unsigned long
+boosted_cpu_util(int cpu)
+{
+ unsigned long util = cpu_util(cpu);
+ unsigned long margin = schedtune_cpu_margin(util);
+
+ return util + margin;
+}
+
/*
* find_idlest_group finds and returns the least busy CPU group within the
* domain.
--
2.5.0
--
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