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I am currently working on a project in Android. I want to get the total cpu usage of each and every process. So i am using the contents of "/proc/pid/stat". I referred this answer to get the stats. Now i got all the utime, stime etc., The problem is with the value of "Hertz". The answer says that it is the number of clock ticks per second. I don't get the exact meaning of clock tick even after browsing a lot. What is a clock tick and is it the frequency of the processor? And the answer says that we can get the clock ticks using

sysconf(_SC_CLK_TCK)

I don't know how to use this linux command in Android to get the clock ticks. I have googled it and i couldn't find it. Pls help me with this. And it would be more helpful if there is an example for this clock tick.

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  • Please check this answer superuser.com/questions/101183/what-is-a-cpu-tick Commented Feb 3, 2015 at 6:58
  • Is it true that in a linux system, ticks occur approximately 100 times per second? i.e., 100 clock ticks per second is usual? Commented Feb 3, 2015 at 7:04
  • It depnds on the Hertez set in kernel confiiguration. Commented Feb 3, 2015 at 7:07
  • 1
    This might help you to understand better makelinux.net/books/lkd2/ch10lev1sec2 Commented Feb 3, 2015 at 7:16

1 Answer 1

Reset to default
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100 is the default value set on Linux. And it appears to be unchanged in Android as shown in the sysconf.c source file - code.google.com/archive/p/android-source-browsing/source

If you see line 167, this is what sysconf(_SC_CLK_TCK) will retrun:

case _SC_CLK_TCK: return SYSTEM_CLK_TCK;

The default value for SYSTEM_CLK_TCK is defined as 100

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