Analyze and optimize Android apps power consumption

Intel® Energy Profiler
power analysis for Android*
Alexander Weggerle

Copyright © 2014, Intel Corporation. All rights reserved. *Other names and brands may be claimed as the property of others. Optimization Notice
CPU C-States / P-States
Intel Confidential
2
C1
C2
C3
C4
C5
C6
Pn
P1
P0 CPU
Active
CPU
Sleep
 P0 - CPU active at highest frequency (HFM)
 Pn - CPU active at lowest frequency (LFM)
 C0 - CPU active (In any P-state)
C0
 C1 - Core clock is Off
 C3/C4 - Reduced Voltage, Partial L2 cache flush
 C6 - Core Off, L2 cache flush, state saved to SRAM
The deeper the sleep state
more power saving
but longer to wake up
Power
Higher
Latency
Greater

CPU Sleep States
• Flexible C-States to Select Idle Power Level vs. Responsiveness
Core voltage*
Core clock
PLL
L1 caches
L2 cache
Wakeup time*
Idle power*
C0 C1 C3 C4
off
Active state
off
flushed
off
off
flushed
off
partial flush
active
* Rough approximation
C6
off
off
off
off

Processor Power and Processor Frequency
9
59
109
159
209
259
309
359
0 0,5 1 1,5 2 2,5 3 3,5
Power(w)
Frequency (GHz)
Power vs. Frequency Curve for Single Architecture
Copyright © 2004 Intel Corporation. All rights reserved.
5
Small Increases in Processor Speed
Results in Large Increases in Power

Components of power analysis
Idle vs. Active
 Do nothing efficiently
 Hurry up and get idle.
e.g. Multi-threading (distributing work evenly across cores)
Optimize Sleep Behavior
 Minimize sporadic wakeups.
 Schedule all periodic activities from the app into same wakeup period.
 What is waking h/w from low power states? Why?
Optimize Utilization
 What is active? Why is it active?
 Minimize Polling Loops. Use event driven framework when possible.
 Turn devices off. Open devices can prevent the system from entering power saving state.

Why Minimize Wakeups?
Frequency of software
activity makes big
difference
Long uninterrupted
Idle period, is the key
7
4
5
6
7
8
9
10
11
12
0% 2% 4% 6% 8% 10%
PlatformPower
CPU Utilization
Solid Activity
Fragmented Activity
Consolidate

Types of Analysis
Two flavors of SoCWatch use cases:
Expert analysis of results Comparison of results by non-experts
Focus on area of expertise:
• A specific SoC device
• A specific driver module
• A specific application
• etc…
Look for differences:
• Wakeup frequency
• P/C state changes
• etc…
Best to have a baseline for comparison in all cases

Power Analysis with VTune™
Amplifier for Systems
9

Summary View
6/16/2014
11

C/P States Tab
6/16/2014
12

C - states
6/16/2014
13

Analyze Wakeups
Intel Confidential
14
Find dominant
wakeups

What C-State residency numbers tell you
Residency in the deepest C-state should be >95% @ idle
If you see high residency in C0 state
 CPU is executing instruction
 Next Step: Active Analysis
If you see high residency in the intermediate C-states
 Frequent active/idle transition is keeping CPU from entering deepest
C-state. Possible causes are:
 Application scheduling periodic timer with short period activity
 Application waits for interrupts (from device, IPI) very frequently
15

CPU Power Analysis
Use case: Collecting data from sensor
• Continuously collecting accelerometer data
• Use power analysis to find out impact of sampling frequency
SENSOR_DELAY_FASTEST SENSOR_DELAY_NORMAL
Lowest Power
consumption
High Power
consumption

Component Device States
Find Components Wasting Power
17
Intel Device States:
 DOi0 = On
 DOi1-DOi2 = Intermediate
 D0i3 = Off
Find:
• Which Devices are on/off?
• For this MP3 Playing
video encoder is not used?
• When they got turned on/off?
• When a device is not in use…

Correlate Metrics
to find patterns
19
See all the metrics at once
Find patterns
Find the cause

Depends on which SoC
 C-States
 P-States (CPU frequency)
 SOi States (System State)
 Android Wakelocks
 Temperature (Core, Skin, SoC, PMIC)
 S(outh) C(luster) Device States
 N(orth) C(luster) Device States
20
Potential Collections

Use cases: Idle
Comparison of system running at Idle with a system running at idle without the
ability to go to sleep.
6/16/2014
22

Use cases: Idle
6/16/2014
23
Percentage of time in C6
 Core 1: 62.7%
 Core 0: 63.3%
Reasons for waking up
 Kernel Timer: 4347
 User Timer: 4120
 IRQ 46: 570
 IRQ 93: 557
Frequency is almost 100% at .8 GHz

Use case: Idle – No sleep
6/16/2014
24
We have forced the
target to never
sleep!
If we don’t sleep we
will not get good
battery performance
Minimizing wakeups is
important but it is critical to
remember that if the system is
not going to sleep in the first
place you won’t see the
wakeups!

Use case: Video playback
1080p playback
6/16/2014
25

26
Use Case: Video playback
 Core 1: 2.4%
 Core 0: 2.7%
 User Timer: 630
 IRQ 46: 111
 IRQ 93: 906
Frequency almost 58.9% at 2 GHz

Use case: Video playback
6/16/2014
27
Most of the
time we spend
in C0 during
video
playback.
Video starts here,
you can filter and
only see wakeups
during playback.

Use case: AWS Fish tank test
6/16/2014
28
The Browser is
actively drawing fish
only in the light
green region.
Otherwise the
frequency drops
and we have a
regular periods
where the
processor is in
C6.

Use case: AWS Fish tank test
6/16/2014
29
 Core 1: 47%
 Core 0: 48%
 User Timer: 4120
 IRQ 46: 570
 IRQ 93: 557

Use Case: AWS An3DBenchXL
6/16/2014
30
Dragon Flowers
Walking
Man

Use Case: AWS An3DBenchXL
Compare OpenGL ES 1.1 with ES 2.0
6/16/2014
31

Use Case: Audio playback
Mp3 Audio playback scenario
Initial view Filtered and zoomed
Freq = 47ms
VTune Amplifier can help find causes for wakeups and their frequencies

mp3-nousb-screen-off mp3-screen-off
150 wakeups/sec 197 wakeups/sec
With no usb connection intel_pmu_driver can put platform in s0i3 state
Use Case: Audio playback
Audio playback –Another scenario

Check if these are within expected range are not
Expert Analysis
Video Recording on CLT+ - Summary

Why is display driver waking up both the CPUs ?
Use Case: Video recording
Video Recording on CLT+ - Display Driver
Wakeup
s
Filter+Zoom

Comparisons/Regression Tests
WAKEUPS
C6 Residency
Pn Residency
Wakelocks
VTune Amplifier Views

Comparisons
Native Video Playback vs 3rd Party Application
Which is “Better”?
Native Video Playback
3rd Party Application

Comparisons
Native Video Playback vs 3rd Party Application
Much more time spent in C0 for the 3rd part application
Native Video Playback
3rd Party Application

Comparisons
Adding a new Kernel Driver
Note the Wake-up Counts
Idle Workload

Comparisons
Note the Wake-up Counts
New Driver

Comparisons
VTune Amplifier Comparison Feature
Reduce the kernel logging (printk) in driver
void my_timer_callback( unsigned long data )
{
int i,j,ret;
for (i=0;i<5000000;i++) {
for (j=0;j<5000000;j++) {
sum=sum+i;
printk( "my_timer_callback called %dn", count );
}}
// setup the timer again to fire 500ms
if (count <50) {
setup_timer( &my_timer, my_timer_callback, 0 );
ret = mod_timer( &my_timer, jiffies +
msecs_to_jiffies(500) );
if (ret) printk("Error in
my_timer_callbackn");
count++;
}
}
void my_timer_callback( unsigned long data )
{
int i,j,ret;
for (i=0;i<5000000;i++) {
for (j=0;j<5000000;j++) {
sum=sum+i;
//printk( "my_timer_callback called %dn", count );
}}
// setup the timer again to fire 500ms
if (count <50) {
setup_timer( &my_timer, my_timer_callback, 0 );
ret = mod_timer( &my_timer, jiffies +
msecs_to_jiffies(500) );
if (ret) printk("Error in my_timer_callbackn");
count++;
}
else {
printk( "callback called %d timesn",count);
}
}

Comparisons
VTune Amplifier Comparison Feature
Reduce the kernel logging (printk) in driver
Reduced total C0 time

References
https://lesswatts.org
6/16/2014
44

Legal Disclaimer & Optimization Notice
INFORMATION IN THIS DOCUMENT IS PROVIDED “AS IS”. NO LICENSE, EXPRESS OR IMPLIED, BY ESTOPPEL OR OTHERWISE, TO
ANY INTELLECTUAL PROPERTY RIGHTS IS GRANTED BY THIS DOCUMENT. INTEL ASSUMES NO LIABILITY WHATSOEVER AND
INTEL DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY, RELATING TO THIS INFORMATION INCLUDING LIABILITY OR
WARRANTIES RELATING TO FITNESS FOR A PARTICULAR PURPOSE, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT,
COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT.
Software and workloads used in performance tests may have been optimized for performance only on Intel microprocessors.
Performance tests, such as SYSmark and MobileMark, are measured using specific computer systems, components, software,
operations and functions. Any change to any of those factors may cause the results to vary. You should consult other
information and performance tests to assist you in fully evaluating your contemplated purchases, including the performance of
that product when combined with other products.
Copyright © 2014, Intel Corporation. All rights reserved. Intel, Pentium, Xeon, Xeon Phi, Core, VTune, Cilk, and the Intel logo are
trademarks of Intel Corporation in the U.S. and other countries.
Optimization Notice
Intel’s compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel
microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the
availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent
optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture
are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the
specific instruction sets covered by this notice.
Notice revision #20110804
45

Analyze and optimize Android apps power consumption

Analyze and optimize Android apps power consumption

Recommandé

Recommandé

Contenu connexe

Similaire à Analyze and optimize Android apps power consumption

Similaire à Analyze and optimize Android apps power consumption (20)

Plus de DroidConTLV

Plus de DroidConTLV (20)

Dernier

Dernier (20)

Analyze and optimize Android apps power consumption