[CentOS] Find reason for heavy load

Chan Chung Hang Christopher christopher.chan at bradbury.edu.hk
Thu Dec 31 12:07:42 UTC 2009


Christoph Maser wrote:
> Am Donnerstag, den 31.12.2009, 12:34 +0100 schrieb Chan Chung Hang
> Christopher:
>>>> Look at the first two columns.  What column have higher numbers?  If r,
>>>> you're CPU-bound.  If b, you're I/O bound.
>>> procs -----------memory---------- ---swap-- -----io---- --system--
>>> -----cpu------
>>>  r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
>>>  8  1   3092 131460 100692 833668    0    0    40    21    1    0  4  1 92  2  0
>>>  9  1   3092 130708 100700 835016    0    0   578   206  577 1420 32 50  3 15  0
>>>  7  1   3092 128324 100716 836148    0    0   546  2866  594 1465 31 44  7 18  0
>>>  4  1   3092 126860 100724 837268    0    0   540   256  596 1505 28 43  6 23  0
>>>  7  2   3092 125600 100740 838564    0    0   620   234  661 1442 30 41  2 26  0
>>>  5  1   3092 124028 100756 839752    0    0   570  2692  635 1430 24 45  6 25  0
>>>  6  0   3092 122040 100784 840964    0    0   584  1464  682 1434 27 44  2 28  0
>>>  6  1   3092 120588 100792 842232    0    0   602   278  624 1562 32 46  2 20  0
>>>  2  3   3092 120556 100840 843064    0    0   440  2908  603 1299 22 35  6 37  0
>>>  3  1   3092 119832 100876 844088    0    0   430  1104  605 1348 23 36  1 40  0
>>>
>>> According to this, am I correct to conclude that I'm CPU bound and the
>>> system is busy doing some unknown processing?
>> Yes, these figures indicate that you are fairly close to being cpu bound.
> 
> 
> Really? 20-30% user and ~40% sys/wait look more like I/O to mee.
> 

user accounts for processing done by processes while sys accounts for 
processing done by the kernel (like netfilter) and idle tells you what 
is left. idle numbers are below 10 and near 0, that would be what I'd 
call nearly cpu bound. If he has high idle scores and high wa scores, 
then he'd be completely i/o bound.

The last line there, he got a idle score of 1 while wa was 40 which 
indicates that even though if there is some i/o waiting, it is not 
starving the cpus.


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