Why is the number of ticks inaccurate?
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I checked the numbers in proc/stat to the the number of clock ticks the CPU has had and I saw that the sum of the numbers in CPU1-4 is not equal to the numbers written in front of CPU as a whole. Why is that?
cpu proc time stat clock
edited Nov 10 '17 at 13:08
SatÃ…Â Katsura
10.7k11533
asked Nov 10 '17 at 8:06
yukashima huksay
429217
add a comment |Â
up vote
1
down vote
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I checked the numbers in proc/stat to the the number of clock ticks the CPU has had and I saw that the sum of the numbers in CPU1-4 is not equal to the numbers written in front of CPU as a whole. Why is that?
cpu proc time stat clock
edited Nov 10 '17 at 13:08
SatÃ…Â Katsura
10.7k11533
asked Nov 10 '17 at 8:06
yukashima huksay
429217
add a comment |Â
up vote
1
down vote
favorite
up vote
1
down vote
favorite
I checked the numbers in proc/stat to the the number of clock ticks the CPU has had and I saw that the sum of the numbers in CPU1-4 is not equal to the numbers written in front of CPU as a whole. Why is that?
cpu proc time stat clock
edited Nov 10 '17 at 13:08
SatÃ…Â Katsura
10.7k11533
asked Nov 10 '17 at 8:06
yukashima huksay
429217
I checked the numbers in proc/stat to the the number of clock ticks the CPU has had and I saw that the sum of the numbers in CPU1-4 is not equal to the numbers written in front of CPU as a whole. Why is that?
cpu proc time stat clock
edited Nov 10 '17 at 13:08
SatÃ…Â Katsura
10.7k11533
asked Nov 10 '17 at 8:06
yukashima huksay
429217
edited Nov 10 '17 at 13:08
SatÃ…Â Katsura
10.7k11533
edited Nov 10 '17 at 13:08
SatÃ…Â Katsura
10.7k11533
edited Nov 10 '17 at 13:08
SatÃ…Â Katsura
10.7k11533
10.7k11533
asked Nov 10 '17 at 8:06
yukashima huksay
429217
asked Nov 10 '17 at 8:06
yukashima huksay
429217
asked Nov 10 '17 at 8:06
yukashima huksay
429217
429217
add a comment |Â
add a comment |Â
1 Answer
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The difference results from truncating the values after calculating the sums. /proc/stat calculates the sums of elapsed times in nanoseconds, and then converts the resulting values to USER_HZ using integer division which truncates.
Thus if all four CPUs have individual values of 1.3, you’ll get a sum of 5.2, truncated to 5 for the first line, and 1 for each CPU line.
answered Nov 10 '17 at 8:37
Stephen Kitt
143k22312377
add a comment |Â
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
3
down vote
accepted
The difference results from truncating the values after calculating the sums. /proc/stat calculates the sums of elapsed times in nanoseconds, and then converts the resulting values to USER_HZ using integer division which truncates.
Thus if all four CPUs have individual values of 1.3, you’ll get a sum of 5.2, truncated to 5 for the first line, and 1 for each CPU line.
answered Nov 10 '17 at 8:37
Stephen Kitt
143k22312377
add a comment |Â
up vote
3
down vote
accepted
The difference results from truncating the values after calculating the sums. /proc/stat calculates the sums of elapsed times in nanoseconds, and then converts the resulting values to USER_HZ using integer division which truncates.
Thus if all four CPUs have individual values of 1.3, you’ll get a sum of 5.2, truncated to 5 for the first line, and 1 for each CPU line.
answered Nov 10 '17 at 8:37
Stephen Kitt
143k22312377
add a comment |Â
up vote
3
down vote
accepted
up vote
3
down vote
accepted
The difference results from truncating the values after calculating the sums. /proc/stat calculates the sums of elapsed times in nanoseconds, and then converts the resulting values to USER_HZ using integer division which truncates.
Thus if all four CPUs have individual values of 1.3, you’ll get a sum of 5.2, truncated to 5 for the first line, and 1 for each CPU line.
answered Nov 10 '17 at 8:37
Stephen Kitt
143k22312377
The difference results from truncating the values after calculating the sums. /proc/stat calculates the sums of elapsed times in nanoseconds, and then converts the resulting values to USER_HZ using integer division which truncates.
Thus if all four CPUs have individual values of 1.3, you’ll get a sum of 5.2, truncated to 5 for the first line, and 1 for each CPU line.
answered Nov 10 '17 at 8:37
Stephen Kitt
143k22312377
answered Nov 10 '17 at 8:37
Stephen Kitt
143k22312377
answered Nov 10 '17 at 8:37
Stephen Kitt
143k22312377
answered Nov 10 '17 at 8:37
Stephen Kitt
143k22312377
143k22312377
add a comment |Â
add a comment |Â
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