diff options
| author | Morten Rasmussen <morten.rasmussen@arm.com> | 2016-03-30 14:20:12 +0100 |
|---|---|---|
| committer | Andres Oportus <andresoportus@google.com> | 2017-06-02 08:01:52 -0700 |
| commit | 02cbde61f4d895c25a422813b066d5537f8812fa (patch) | |
| tree | 52240f2aa1e5068f47a0dc521cbb72ffa68b7350 /kernel/sched | |
| parent | 3b6ba235bcf3827d4911f3eb27bae5ac0f4dbbc8 (diff) | |
sched/fair: Add energy_diff dead-zone margin
It is not worth the overhead to migrate tasks for tiny insignificant
energy savings. To prevent this, an energy margin is introduced in
energy_diff() which effectively adds a dead-zone that rounds tiny energy
differences to zero. Since no scale is enforced for energy model data
the margin can't be absolute. Instead it is defined as +/-1.56% energy
saving compared to the current total estimated energy consumption.
Change-Id: I6be069c752c701fb825430896b3b768a7ab2fee4
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
[rebase: on top of msm-google/android-msm-marlin-3.18,
massage original patch which changes code in energy_diff()
into __energy_diff() introduced by SchedTune]
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
(cherry picked from commit 780cb5a5fa47adf13d4fc2b77e8e94448cd56098)
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/fair.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index ef16d4d3cc00..16f15549b5d0 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5149,6 +5149,7 @@ static inline int __energy_diff(struct energy_env *eenv) struct sched_domain *sd; struct sched_group *sg; int sd_cpu = -1, energy_before = 0, energy_after = 0; + int diff, margin; struct energy_env eenv_before = { .util_delta = 0, @@ -5198,6 +5199,16 @@ static inline int __energy_diff(struct energy_env *eenv) eenv->cap.before, eenv->cap.after, eenv->cap.delta, eenv->nrg.delta, eenv->payoff); + /* + * Dead-zone margin preventing too many migrations. + */ + + margin = eenv->nrg.before >> 6; /* ~1.56% */ + + diff = eenv->nrg.after - eenv->nrg.before; + + eenv->nrg.diff = (abs(diff) < margin) ? 0 : eenv->nrg.diff; + return eenv->nrg.diff; } |