How to read the Stock CPU Usage data

Question

On Ice Cream Sandwich  an option in the Developer Options is  Show CPU Usage   which adds an overlay on the screen  see screenshot below     My question is  how do I read the data   I guessed that the package names are the process currently actives  but what does the red and green bars behind mean    Also what are the 3 numbers on top of the packages

User · Answer

From High Performance Android Apps book  page 157     what we see is equivalent of adb shell dumpsys cpuinfo command Numbers are showing CPU load over 1 minute  5 minutes and 15 minutes  from the left  Colors are showing time spent by CPU in user space  green   kernel  red  and IO interrupt  blue

User · Answer

So far this has been the most helpful source of information regarding this I could find  Apparently the numbers do NOT reperesent load average in    http   forum xda-developers com showthread php t 1495763

User · Answer

This should be the Unix load average  Wikipedia has a nice article about this   The numbers show the average load of the CPU in different time intervals  From left to right  last minute last five minutes last fifteen minutes

User · Answer

More about  load average  showing CPU load over 1 minute  5 minutes and 15 minutes   Linux  Mac  and other Unix-like systems display    load average    numbers  These numbers tell you how busy your system   s CPU  disk  and other resources are  They   re not self-explanatory at first  but it   s easy to become familiar with them   WIKI  example  one can interpret a load average of  1 73 0 60 7 98  on a single-CPU system as   during the last minute  the system was overloaded by 73  on average  1 73 runnable processes  so that 0 73 processes had to wait for a turn for a single CPU system on average   during the last 5 minutes  the CPU was idling 40  of the time on average  during the last 15 minutes  the system was overloaded 698  on average  7 98 runnable processes  so that 6 98 processes had to wait for a turn for a single CPU system on average  if dual core mean  798  - 200    598      You probably have a system with multiple CPUs or a multi-core CPU  The load average numbers work a bit differently on such a system  For example  if you have a load average of 2 on a single-CPU system  this means your system was overloaded by 100 percent     the entire period of time  one process was using the CPU while one other process was waiting  On a system with two CPUs  this would be complete usage     two different processes were using two different CPUs the entire time  On a system with four CPUs  this would be half usage     two processes were using two CPUs  while two CPUs were sitting idle   To understand the load average number  you need to know how many CPUs your system has  A load average of 6 03 would indicate a system with a single CPU was massively overloaded  but it would be fine on a computer with 8 CPUs   more info   Link

User · Answer

As other answers have pointed  on UNIX systems the numbers represent CPU load averages over 1 5 15 minute periods  But on Linux  and consequently Android   what it represents is something different  After a kernel patch dating back to 1993  a great in-depth article on the subject   in Linux the load average numbers no longer strictly represent the CPU load  as the calculation accounts not only for CPU bound processes  but also for processes in uninterruptible wait state - the original goal was to account for I O bound processes this way  to represent more of a  quot system load quot  than just CPU load  The issue is that since 1993 the usage of uninterruptible state has grown in Linux kernel  and it no longer typically represents an I O bound process  The problem is further exacerbated by some Linux devs using uninterruptible waits as an easy wait to avoid accommodating signals in their implementations  As a result  in Linux  and Android  we can see skewed high load average numbers that do not objectively represent the real load  There are Android user reports about unreasonable high load averages contrasting low CPU utilization  For example  my old Android phone  with 2 CPU cores  normally shown average load of  12 even when the system and CPUs were idle  Hence  average load numbers in Linux  Android  does not turn out to be a reliable performance metric

[android] How to read the Stock CPU Usage data

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