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Rebalancing at exec time will currently undo any beneficial placement
that has been done during fork time, since select_best_cpu() will not
discount the currently running task.
For now just skip re-evaluating task placement at exec.
Change-Id: I1e5e0fcc329b7b53c338c8c73795ebd5e85a118b
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
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Historical load maintained per task can be used to influence cpu
frequency better. For example, when a heavy demand task wakes up after
prolonged sleep, we could use the historical load information to alert
cpufreq governor about the need to raise cpu frequency. This patch
changes CPU busy statistics to be aggregation of historical task
demand. Also task's historical load (as defined by
sysctl_sched_window_stats_policy) is add to cpu's busy statistics
(rq->curr_runnable_sum) whenever it executes on a cpu.
Change-Id: I2b66136f138b147ba19083b9b044c4feb20d9b57
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[rameezmustafa@codeaurora.org]: Port to msm-3.18]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org
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In the event that a full window (or multiple full windows) have
elapsed when updating a task's window-based stats, the runtime of
those windows needs to be scaled based on the CPU frequency. This
is currently missing, causing full windows to be accounted as having
elapsed at maximum frequency, erroneously inflating task demand.
Change-Id: I356b4279d44d4f39c8aea881c04327b70ed66183
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
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After a migration occurs the source and destination CPUs may
not be running at frequencies which match the new task load on
those CPUs.
Previously, the scheduler was notifying cpufreq anytime a task
greater than a certain size migrates. This is suboptimal however
since this does not take into account the CPU's current
frequency and other task activity that may be present.
Change-Id: I5092bda3a517e1343f97e5a455957c25ee19b549
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
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When the number of tasks intended for a cluster exceed the number of
mostly idle CPUs in that cluster, the scheduler currently freely uses
CPUs in other clusters if possible. While this is optimal for
performance the power trade off can be quite significant. Introduce
spill threshold tunables that govern the extent to which the scheduler
should attempt to contain tasks within a cluster.
Change-Id: I797e6c6b2aa0c3a376dad93758abe1d587663624
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
[rameezmustafa@codeaurora.org]: Port to msm-3.18]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org
[joonwoop@codeaurora.org: fixed conflict in nohz_kick_needed()]
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
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Knowing the affinity mask and CPU usage of a task is helpful
in understanding the behavior of the system. Affinity information
has been added to the enq_deq trace event, and the migration
tracepoint now reports the load of the task migrated.
Change-Id: I29d8a610292b4dfeeb8fe16174e9d4dc196649b7
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
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When a task moves between CPUs in two different frequency domains
the cpufreq governor may wish to immediately modify the frequency
of both the source and destination CPUs of the migrating task.
A tunable is provided to establish what size task is considered
"significant" enough to warrant notifying cpufreq.
Also fix a bug that would cause load to not be accounted properly
during wakeup migrations.
Change-Id: Ie8f6b1cc4d43a602840dac18590b42a81327c95a
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
[rameezmustafa@codeaurora.org: Add double rq locking for set_task_cpu()]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
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Should the system get stuck in a state where load balancing is failing
due to all tasks being pinned, deferring load balancing for up to half
a second may cause further performance problems. Eventually all tasks
will not be pinned and load balancing should not be deferred for a great
length of time.
Change-Id: I06f93b5448353b5871645b9274ce4419dc9fae0f
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
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If we have a task to schedule, we currently don't consider CPUs where
it will not fit even if they are idle. Instead we choose the previous
CPU which is sub-optimal for performance if an idle CPU is
present. This change introduces tracking of any idle CPUs irrespective
of whether the task fits on them or not. If we don't have a good place
to put the task, prefer the lowest power idle CPU.
Change-Id: I4e8290639ad1602541a44a80ba4b2804068cac0f
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[rameezmustafa@codeaurora.org]: Port to msm-3.18]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org
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Real Time task scheduling has historically been geared towards performance
with a significant attempt to keep higher priority tasks on the same CPU.
This is not optimal for power since the task CPU may not be the most
power efficient CPU.
Also task movement via select_lowest_rq() gives CPU priority the primary
consideration before looking at CPU topologies to find a CPU closest to
the task CPU in terms of topology. This again is not optimal for power
since the closest CPU may be significantly worse for power than CPUs
further away.
This patch removes any bias for the task CPU. When the lowest priority
CPUs in the system are found we give no consideration to the CPU topology.
Instead we find the lowest power CPU within local_cpu_mask. This takes care
of select_task_rq_rt() and push_task(). The pull model remains unaffected
since we have no room for power optimization there.
Change-Id: I4162ebe2f74be14240e62476f231f9e4a18bd9e8
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[joonwoop@codeaurora.org: s/__get_cpu_var/this_cpu_ptr/]
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
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Normally the load balancer does not pay attention to CPUs with one
task since it is not possible to subdivide that load any further
to achieve better balance. With power aware scheduling however it
may be desirable to relocate that one task if the CPU it is currently
executing on is less power efficient than other CPUs in the system.
Change-Id: Idf3f5e22b88048184323513f0052827b884526b6
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[rameezmustafa@codeaurora.org]: Port to msm-3.18]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org
[joonwoop@codeaurora.org: group_capacity_factor changed to
group_no_capacity. group_classify is called by update_sg_lb_stats() too.]
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
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Although tasks are routed to the most power-efficient CPUs during
task wakeup, a CPU-bound task will not go through this decision point.
Load balancing can help if it is modified to dislodge a single task
from an inefficient CPU. The situation can be further improved if
during the tick, the task placement is checked to see if it is
optimal.
This sort of checking is already being done to ensure proper
task placement in heterogneous CPU topologies, so checking for
power efficient task placement fits pretty well.
Change-Id: I71e56d406d314702bc26dee1438c0eeda7699027
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
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The nohz load balancer CPU does load balancing on behalf of all
idle tickless CPUs. In the interest of power efficiency though, we
should do load balancing on the most power efficient idle tickless
CPU first, and then work our way towards the least power efficient
idle tickless CPU. This will help load find its way to the most
power efficient CPUs in the system.
Since when selecting the CPU to balance next it is unknown what
task load would be pulled, a frequency must be assumed in order
to do a comparison of CPU power consumption. The maximum
freqeuncy supported by all CPUs is used for this.
Change-Id: I96c7f4300fde2c677c068dc10fc0e57f763eb9b2
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[joonwoop@codeaurora.org: fixed minor conflict in nohz_idle_balance().]
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
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When a CPU goes idle, it checks to see whether it can pull any load
from other busy CPUs. The CPU going idle may not be the most
power-efficient idle CPU in the system however.
This patch causes the CPU going idle to check to see whether
there is a more power-efficient idle CPU within the same
lowest sched domain. If there is, then it runs the load balancer
on behalf of that CPU instead of itself.
Since it is unknown at this point what task load would be pulled,
a frequency must be assumed for this in order to do a comparison
of CPU power consumption. The maximum freqeuncy supported by all
CPUs is used for this.
Change-Id: I5eedddc1f7d10df58ecd358f37dba563eeecf4fc
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[rameezmustafa@codeaurora.org]: Port to msm-3.18]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org
[joonwoop@codeaurora.org: fixed minor conflict around comment.]
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
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To enable power-aware scheduling, provide a hook/infrastructure
for platforms to communicate CPU power requirements for each
supported CPU frequency. This information is then used to estimate
the cost of running a task on a given CPU.
Currently, an assumption is made that the task will be running
by itself on the CPU. Given the current policy tries to spread
tasks as much as possible this assumption should not be too
far off.
Change-Id: I19f1fa760a0d43222d2880f8aec0508c468b39bb
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[joonwoop@codeaurora.org: return rq->capacity as power cost with
sched_use_pelt=1. se.avg.runnable_avg_period is deprecated and
power_cost() will be changed by subsequent change anyway./
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
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The sched_enable_power_aware sysctl will control whether
or not scheduling decisions are influenced by the power
consumption of individual CPUs.
Change-Id: I312f892cf76a3fccc4ecc8aa6703908b205267f0
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
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This will make it easier to account interrupt time on a cpu,
introduced in a subsequent patch.
Change-Id: I0e1fb5255c280ca374fd255e7fc19d5de9f8b045
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[rameezmustafa@codeaurora.org]: Port to msm-3.18]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org
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sched_get_busy() returns the busy time of a cpu during the most
recent completed window.
sched_set_window() will set window size and aligns windows across
all CPUs.
Change-Id: Ic53e27f43fd4600109b7b6db979e1c52c7aca103
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
[joonwoop@codeaurora.org: fixed minor conflict in include/linux/sched.h]
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
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Adjust cpu's busy time in its recent and previous window upon task
migration. This would enable scheduler to provide better inputs to
cpufreq governor on a cpu's busy time in a given window.
Change-Id: Idec2ca459382e9f46d882da3af53148412d631c6
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
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Add counters per-cpu to track its busy time in the latest window and
one previous to that. This would be needed to track accurate busy time
per-cpu that accounts for migrations. Basically once a task migrates,
its execution time in current window is migrated as well to new cpu.
The idle task's runtime is not accounted since it should not count
towards runqueue busy time.
Change-Id: I4014dd686f95dbbfaa4274269bc36ed716573421
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
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Currently windows where tasks had no execution time are ignored.
However accurate accounting of cpu busy time that factors in migration
would need to know actual utilization of a task in the window previous
to the latest one. This would help scheduler guide cpufreq governor on
busy time per-cpu that is not subject to migration induced errors.
Change-Id: I5841b1732c83e83d69002139de3bdb93333ce347
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
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Synchronizing windows across cpus for task load measurements
simplifies cpu busy time accounting during migrations. For task
migrations, its usage in current window can be carried over to its new
cpu. This lets cpufreq governor see a correct picture of cpu busy time
that is not affected by migrations.
This patch lines up windows across cpus. One of the cpu, sync_cpu,
serves as a reference for all others. During bootup sync_cpu would
initialize its window_start (from its sched_clock()). Other cpus will
synchronize their window_start in reference to sync_cpu. This patch
assumes synchronous sched_clock() across cpus and may need some change
to address architectures which do not provide such synchronized
sched_clock().
Change-Id: I13381389a72f5f9f85cc2446401d493a55c78ab7
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
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Task load statistics are used for two purposes : cpu frequency
management and placement. Task's load can't be accurately judged by
its wait time. For ex: a task could have waited for 10ms and when given
opportunity to run, could just execute for 1ms. Accounting for 11ms as
task's demand could be over-stating its needs in this example. For
now, remove wait time from task demand and instead let task load be
derived from its actual exec time. This may need to become a tunable
feature.
Change-Id: I47e94c444c6b44c3b0810347287d50f1ee685038
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
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During migrations accounting needs to be done in set_task_cpu() to
subtract the task activity from the source CPU and add it to the
destination CPU. This accounting will require that the task's window
based load statistics be up to date.
Unfortunately, the window-based statistics cannot always be updated in
set_task_cpu() because they are already being updated in the wakeup
path. We cannot update the statistics solely in the wakeup path
because not all wakeups are migrations. Those non-migrating wakeups
will not enter set_task_cpu().
To ensure the window-based stats are always updated for both wakeup
migrations and regular migrations, they are updated earlier in the
wakeup path, and also updated in set_task_cpu if the task is already
runnable (this ensures it is not a wakeup migration, but a regular
migration).
Change-Id: Ib246028741d0be9bb38ce93679d6e6ba25b10756
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[rameezmustafa@codeaurora.org]: Port to msm-3.18]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
[joonwoop@codeaurora.org: fixed minor conflict in fair.c]
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
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set_task_cpu() will need to call update_task_ravg(). Move up
definition to make it easy.
Change-Id: I95c1c9e009bd1805f28708e8d6fd3b7b2166410e
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[rameezmustafa@codeaurora.org]: Port to msm-3.18]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
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Set window-based load stats to be the default mechanism under which
tasks get classified (as big/small) and which will drive frequency
demand for tasks. sched_ravg_window kernel parameter can be used to
change this default setting to use PELT (per-entity load tracking)
scheme instead.
Change-Id: I626110daa0bb2b53172bedea829d31877255ceaa
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
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Provide a runtime tunable to switch between using PELT-based load
stats and window-based load stats. This will be needed for runtime
analysis of the two load tracking schemes.
Change-Id: I018f6a90b49844bf2c4e5666912621d87acc7217
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
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Extend "sched" file in /proc for every task to provide information on
scaled load statistics and percentage-scaled based load (load_avg) for
a task. This will be valuable debug aid.
Change-Id: I6ee0394b409c77c7f79f5b9ac560da03dc879758
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
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This patch adds two ftrace events:
sched_task_load -> records information of a task, such as scaled demand
sched_cpu_load -> records information of a cpu, such as nr_running,
nr_big_tasks etc
This will be useful to debug HMP related task placement decisions by
scheduler.
Change-Id: If91587149bcd9bed157b5d2bfdecc3c3bf6652ff
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
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Provide additional information in /proc/sched_debug for every cpu.
This will be a valuable debug aid.
Change-Id: If22ee530e880cd21719242be7bc2c41308ad4186
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[rameezmustafa@codeaurora.org]: Port to msm-3.18]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
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Several conditions can cause an idle cluster to pick up load from a
busy cluster. One such condition is when busy cluster has number of
tasks that exceeds its capacity (or number of cpus). This patch
extends that condition to consider small and big tasks on a cluster.
Too many "small" tasks should not cause them to spill over to another
idle cluster. Like-wise presence of big tasks should be considered
by a cluster to pick up load from another another cluster with lower
capacity.
Change-Id: I0545bf2989c37217d84ed18756c6f5c8946d5ae5
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
[rameezmustafa@codeaurora.org]: Port to msm-3.18]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
[joonwoop@codeaurora.org: fixed minior conflict in fair.c.]
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
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This patch adds 'nr_big_tasks' and 'nr_small_tasks' per-cpu counters
that tracks number of big and small tasks on a cpu respectively. This
will be used in load balance decisions introduced in a subsequent
patch.
Change-Id: Ia174904140f81dd6d1946286889a50be3f16ea83
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[rameezmustafa@codeaurora.org]: Port to msm-3.18]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
[joonwoop@codeaurora.org: fix conflicts in fair.c]
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
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CPU-bound tasks that don't sleep for long intervals can stay stuck on
the wrong cpu, as the selection of "ideal" cpu for tasks largely
happens during task wakeup time. This patch adds a check in the
scheduler tick for task/cpu mismatch (big task on little cpu OR
little task on big cpu) and forces migration of such tasks to their
ideal cpu (via select_best_cpu()).
Change-Id: Icac3485b6aa4b558c4ed9df23c2e81fb8f4bb9d9
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
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Active balance currently picks one task to migrate from busy cpu to
a chosen cpu (push_cpu). This patch extends active load balance to
recognize a particular task ('push_task') that needs to be migrated to
'push_cpu'. This capability will be leveraged by HMP-aware task
placement in a subsequent patch.
Change-Id: If31320111e6cc7044e617b5c3fd6d8e0c0e16952
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[rameezmustafa@codeaurora.org]: Port to msm-3.18]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
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A busy cpu will kick (via IPI) one of the idle cpus in tickless state
to run load balance and help move tasks off itself. The cpu chosen to
receive kick is simply the "first" idle cpu found in
nohz.idle_cpus_mask. This could cause unnecessary wakeups of a
cluster. A better choice would be to look for an idle cpu that is in
the same cluster as busy cpu, which should minimize cluster wakeups.
Change-Id: Ia63038d7c34b416b53c8feef3c3b31dab5200e42
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[rameezmustafa@codeaurora.org]: Port to msm-3.18]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
[joonwoop@codeaurora.org: fixed minor conflict about return value.]
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
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HMP systems have cpus with different power and performance
characteristics. Some cpus could offer better power at cost of lower
performance while other cpus could offer better performance at cost of
higher power. As a result, bandwidth consumed by a task to do some
"fixed" amount of work could vary across cpus.
Optimal task placement on HMP would involve placing a task on a cpu
where it can meet its performance goals at lowest power cost. Since
kernel has little to no awareness of performance goals of
applications, we guestimate whether task is meeting its performance
goals or not by looking at its cpu bandwidth consumption. High
bandwidth consumption could imply that task's performance can improve
by running on cpus with better capacity/performance-characterisitcs.
This patch makes the basic changes to support HMP. It provides a
configurable threshold and any task consuming bandwidth in excess of
threshold will be placed on a cpu with better capacity.
Change-Id: I3fd98edd430f73342fbef06411e8b2d1cf2f56fa
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[rameezmustafa@codeaurora.org]: Port to msm-3.18]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
[joonwoop@codeaurora.org: fixed conflict about members of p->se which
are not available anymore.]
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
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Extend task load scaling function to account for cpu efficiency
factor. Task load is scaled in reference to "most" efficient cpu.
Change-Id: I7bf829211a6e1293076e8ba0f93b4f6abcf20d92
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
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Efficiency reflects instructions per cycle capability of a cpu.
load_scale_factor reflects magnification factor that is applied for
task load when estimating bandwidth it will consume on a cpu. It
accounts for the fact that task load is scaled in reference to "best"
cpu that has best efficiency factor and also best possible max_freq.
Note that there may be no single CPU in the system that has both the
best efficiency and best possible max_freq, but that is still the
combination that all task load in the system is scaled against.
capacity reflects max_freq and efficiency metric of a cpu. It is
defined such that the "least" performing cpu (one with lowest
efficiency factor and max_freq) gets capacity of 1024. Again, there
may not be a CPU in the system that has both the lowest efficiency
and lowest max_freq. This is still the combination that is assigned
a capacity of 1024 however, other CPU capacities are relative to this.
Change-Id: I4a853f1f0f90020721d2a4ee8b10db3d226b287c
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[rameezmustafa@codeaurora.org]: Port to msm-3.18]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
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Add a compile-time flag to enable or disable scheduler features for
HMP (heterogenous multi-processor) systems. Main feature deals with
optimizing task placement for best power/performance tradeoff.
Also extend features currently dependent on CONFIG_SCHED_FREQ_INPUT to
be enabled for CONFIG_HMP as well.
Change-Id: I03b3942709a80cc19f7b934a8089e1d84c14d72d
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[rameezmustafa@codeaurora.org]: Port to msm-3.18]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
[joonwoop@codeaurora.org: fixed minor ifdefry conflict.]
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
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Scheduler guided frequency selection as well as task placement on
heterogeneous systems require scaled task load statistics. This patch
adds a 'runnable_avg_sum_scaled' metric per task that is a scaled
derivative of 'runnable_avg_sum'. Load is scaled in reference to
"best" cpu, i.e one with best possible max_freq
Change-Id: Ie8ae450d0b02753e9927fb769aee734c6d33190f
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[rameezmustafa@codeaurora.org]: Port to msm-3.18]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
[joonwoop@codeaurora.org: incoporated with change 9d89c257df
(" sched/fair: Rewrite runnable load and utilization average
tracking"). Used container_of() to get sched_entity.]
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
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Introduce a compile time flag to enable scheduler guidance of
frequency selection. This flag is also used to turn on or off
window-based load stats feature.
Having a compile time flag will let some platforms avoid any
overhead that may be present with this scheduler feature.
Change-Id: Id8dec9839f90dcac82f58ef7e2bd0ccd0b6bd16c
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[rameezmustafa@codeaurora.org]: Port to msm-3.18]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
[joonwoop@codeaurora.org: fixed minor conflict around
sysctl_timer_migration.]
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
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Following cleanups and improvements are made to window-based load
stats feature:
* Add sysctl to pick max, avg or most recent samples as task's
demand.
* Fix overflow possibility in calculation of sum for average policy.
* Use unscaled statistics when a task is running on a CPU which is
thermally throttled.
Change-Id: I8293565ca0c2a785dadf8adb6c67f579a445ed29
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
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rq->max_possible_freq represents the maximum frequency a cpu is
capable of attaining, while rq->max_freq represents the maximum
frequency a cpu can attain at a given instant. rq->max_freq includes
constraints imposed by user or thermal driver.
rq->max_freq <= rq->max_possible_freq.
max_possible_freq is derived as max(rq->max_possible_freq) and
represents the "best" cpu that can attain best possible frequency.
min_max_freq is derived as min(rq->max_possible_freq). For homogeneous
systems, max_possible_freq and min_max_freq will be same, while they
could be different on heterogeneous systems.
Change-Id: Iec485fde35cfd33f55ebf2c2dce4864faa2083c5
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[joonwoop@codeaurora.org: fixed conflict around max_possible_freq.]
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
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The task load based functions will need to make use of LOAD_AVG_MAX
in a subsequent patch, so move them below the definition of that
macro.
Change-Id: I02f18ba069b81033e611f8f8bba6dccd7cd81252
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
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Until a task's state has been seen as interruptible/uninterruptible
and it is no longer on_cpu, it is possible that the task may move
to another CPU (load balancing may cause this). Here is an example
where the race condition results in incorrect operation:
- cpu 0 calls put_prev_task on task A, task A's state is TASK_RUNNING
- cpu 0 runs task B, which attempts to wake up A
- cpu 0 begins try_to_wake_up(), recording src_cpu for task A as cpu 0
- cpu 1 then pulls task A (perhaps due to idle balance)
- cpu 1 runs task A, which then sleeps, becoming INTERRUPTIBLE
- cpu 0 continues in try_to_wake_up(), thinking task A's previous
cpu is 0, where it is actually 1
- if select_task_rq returns cpu 0, task A will be woken up on cpu 0
without properly updating its cpu to 0 in set_task_cpu()
CRs-Fixed: 665958
Change-Id: Icee004cb320bd8edfc772d9f74e670a9d4978a99
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
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Load statistics for idle tasks is not useful in any manner. Skip load
update for such idle tasks.
CRs-Fixed: 665706
Change-Id: If3a908bad7fbb42dcb3d0a1d073a3750cf32fcf9
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
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Some tasks can have a sporadic load pattern such that they can suddenly
start running for longer intervals of time after running for shorter
durations. To recognize such sharp increase in tasks' demands, max
between the average of 5 window load samples and the most recent sample
is chosen as the task demand.
Make the window size (sched_ravg_window) configurable at boot up
time. To prevent users from setting inappropriate values for window
size, min and max limits are defined. As 'ravg' struct tracks load for
both real-time and non real-time tasks it is moved out of sched_entity
struct.
In order to prevent changing function signatures for move_tasks() and
move_one_task() per-cpu variables are defined to track the total load
moved. In case multiple tasks are selected to migrate in one load
balance operation, loads > 100 could be sent through migration notifiers.
Prevent this scenario by setting mnd.load to 100 in such cases.
Define wrapper functions to compute cpu demands for tasks and to change
rq->cumulative_runnable_avg.
Change-Id: I9abfbf3b5fe23ae615a6acd3db9580cfdeb515b4
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
Signed-off-by: Rohit Gupta <rohgup@codeaurora.org>
[rameezmustafa@codeaurora.org: Port to msm-3.18 and squash "dcf7256 sched:
window-stats: Fix overflow bug" into this patch.]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
[joonwoop@codeaurora.org: fixed conflict in __migrate_task().]
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
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Add a change to send notify_on_migrate hints on wakeups of
foreground tasks from scheduler if their load is above
wakeup_load_thresholds (default value is 60).
These hints can be used to choose an appropriate CPU frequency
corresponding to the load of the task being woken up.
By default sched_wakeup_load_threshold is set to 60 and therefore
wakeup hints are sent out for those tasks whose loads are higher
that value. This might cause unnecessary wakeup boosts to happen
when load based syncing is turned ON for cpu-boost.
Disable the wake up hints by setting the sched_wakeup_load_threshold
to a value higher than 100 so that wakeup boost doesnt happen unless
it is explicitly turned ON from adb shell.
Change-Id: Ieca413c1a8bd2b14a15a7591e8e15d22925c42ca
Signed-off-by: Rohit Gupta <rohgup@codeaurora.org>
[rameezmustafa@codeaurora.org: Squash "a26fcce sched: Disable wakeup
hints for foreground tasks by default" into
this patch and update commit text.]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
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Previously, on getting a migration notification cpu-boost changed
the scaling min of the destination frequency to match that of the
source frequency or sync_threshold whichever was minimum.
If the scheduler migration notification is extended with task load
(cpu demand) information, the cpu boost driver can use this load to
compute a suitable frequency for the migrating task. The required
frequency for the task is calculated by taking the load percentage
of the max frequency and no sync is performed if the load is less
than a particular value (migration_load_threshold).This change is
beneficial for both perf and power as demand of a task is taken into
consideration while making cpufreq decisions and unnecessary syncs
for lightweight tasks are avoided.
The task load information provided by scheduler comes from a
window-based load collection mechanism which also normalizes the
load collected by the scheduler to the max possible frequency
across all CPUs.
Change-Id: Id2ba91cc4139c90602557f9b3801fb06b3c38992
Signed-off-by: Rohit Gupta <rohgup@codeaurora.org>
[rameezmustafa@codeaurora.org]: Port to msm-3.18]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
[joonwoop@codeaurora.org: fixed conflict in __migrate_task().]
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
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Provide a metric per task that specifies how cpu bound a task is. Task
execution is monitored over several time windows and the fraction of
the window for which task was found to be executing or wanting to run
is recorded as task's demand. Windows over which task was sleeping are
ignored. We track last 5 recent windows for every task and the maximum
demand seen in any of the previous 5 windows (where task had some
activity) drives freq demand for every task.
A per-cpu metric (rq->cumulative_runnable_avg) is also provided which
is an aggregation of cpu demand of all tasks currently enqueued on it.
rq->cumulative_runnable_avg will be useful to know if cpu frequency
will need to be changed to match task demand.
Change-Id: Ib83207b9ba8683cd3304ee8a2290695c34f08fe2
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
[rameezmustafa@codeaurora.org]: Port to msm-3.18]
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>
[joonwoop@codeaurora.org: fixed conflict in ttwu_do_wakeup() to
incorporate with changed trace_sched_wakeup() location.]
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
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