strange walues using

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(10-15-2009, 11:08 PM)lhffan Wrote:  But still it feels strange is there no accurate tool to measure cpu usage.

You can use command:

Code:

vmstat 3

After the first line you see statistics of three second intervals. The first line is average statistics since boot.

Here are the column explanations (in the last --- cpu --- part):

Code:

CPU
       These are percentages of total CPU time.
       us: Time spent running non-kernel code. (user time, including nice time)
       sy: Time spent running kernel code. (system time)
       id: Time spent idle. Prior to Linux 2.5.41, this includes IO-wait time.
       wa: Time spent waiting for IO. Prior to Linux 2.5.41, included in idle.
       st: Time stolen from a virtual machine. Prior to Linux 2.6.11, unknown.

For example here's how it looks on my system:

Code:

vmstat 3
procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa
4  0   9528 215892 207588 2534336    0    0    38   135    0    0 10  1 83  6

1  0   9528 214648 207600 2534472    0    0     0  1121 2043 7994 16  1 83  0
1  1   9528 214040 207636 2534360    0    0     1 23888 2515 3531 12  1 83  4
2  0   9528 213900 207648 2534576    0    0     0   515 2027 4745 16  1 83  0
1  0   9528 201564 207660 2534620    0    0     0   599 2043 3070 14  1 85  0
1  0   9528 201448 207664 2534640    0    0     7   309 1950 3060 15  1 84  0

The important part is the "us" column, which is how much srcds is actually using CPU. System time "sy" column is also important, but it should be very low. Otherwise there is this so called "overhead" running the system. The column "id" means "idle" and should be high, "wa" is "wait" and it should be most of the time 0. If it's not 0, then there is very much disk operations and the system is waiting for the hard disk to spin around.