Re: CPU Load average VS Idle %



howa wrote:
Jean-David Beyer 寫道:

howa wrote:
using the top command, e.g.

top -d 5

the load average is : 2.59, 2.18, 1.90

However, the CPU Idle % is always 9x %

is this normal?

Insufficient data. My machine has a higher load average than yours, but I
have two hyperthreaded processors and four processes are BOINC ones that run
at nice level 19; i.e., only if nothing else wants a processor.

A high load average is not a problem unless it is "too high." For my
machine, that would be anything over 8.

Note here that my iowait is zero because there are always compute-limited
processors that can use a processor. Once in a while this misses for a
moment, but it is rare. Also note that different versions of _top_ look
slightly different, but you should be able to tell what's what.

12:28:30 up 6 days, 13:56, 4 users, load average: 4.22, 4.27, 4.32
134 processes: 128 sleeping, 5 running, 0 zombie, 1 stopped
CPU states: cpu user nice system irq softirq iowait idle
total 8.2% 80.4% 11.3% 0.0% 0.0% 0.0% 0.0%
cpu00 21.3% 65.0% 13.5% 0.0% 0.0% 0.0% 0.0%
cpu01 10.5% 79.8% 9.6% 0.0% 0.0% 0.0% 0.0%
cpu02 0.0% 86.5% 13.4% 0.0% 0.0% 0.0% 0.0%
cpu03 0.9% 90.2% 8.7% 0.0% 0.0% 0.0% 0.0%
Mem: 8208852k av, 7982092k used, 226760k free, 0k shrd, 465608k buff
3698628k actv, 3048256k in_d, 142416k in_c
Swap: 8193076k av, 0k used, 8193076k free 6108852k cached

It would be useful to know what the irq, softirq, iowait, and idle times are
for your machine. If by 9x% you mean 90% and over, it means processes cannot
use the processor because they are waiting for something other than a
processor, and IO is the most common.

more info:

20:56:22 up 250 days, 20:51, 1 user, load average: 4.49, 4.32, 4.13
102 processes: 101 sleeping, 1 running, 0 zombie, 0 stopped
CPU0 states: 5.2% user 0.4% system 0.0% nice 0.0% iowait
93.3% idle
CPU1 states: 5.2% user 1.2% system 0.0% nice 0.0% iowait
92.4% idle
CPU2 states: 8.4% user 1.2% system 0.0% nice 0.0% iowait
89.2% idle
CPU3 states: 5.0% user 0.3% system 0.0% nice 0.0% iowait
94.1% idle
Mem: 3355136k av, 3248108k used, 107028k free, 0k shrd,
111304k buff
1208084k active, 775668k inactive
Swap: 8184188k av, 2124k used, 8182064k free
1870928k cached


2 Xeon CPU, Hyperthreaded

I sure would not expect to see that. It is a lot like mine, but I would
expect you to have a lot of process time in either nice or idle, and you do not.

What does _vmstat_ show? Mine is like this at the moment, and the machine is
not doing much except four BOINC jobs (compute limited, nice 19).

$ vmstat 10
procs memory swap io system cpu
r b swpd free buff cache si so bi bo in cs us sy id wa
5 0 0 363760 472332 6326036 0 0 4 9 6 11 12 5 0 0
5 0 0 381480 472332 6326032 0 0 0 34 217 607 96 4 0 0
4 0 0 335880 472332 6326032 0 0 0 139 164 614 96 4 0 0
4 0 0 335440 472332 6326032 0 0 0 46 125 370 97 3 0 0
6 0 0 324164 472332 6326032 0 0 0 80 124 411 97 3 0 0
4 0 0 348596 472332 6326032 0 0 0 79 121 378 97 3 0 0
5 0 0 317840 472332 6326036 0 0 0 95 251 710 96 4 0 0

(Remember to not rely on the first line of output from vmstat.)

--
.~. Jean-David Beyer Registered Linux User 85642.
/V\ PGP-Key: 9A2FC99A Registered Machine 241939.
/( )\ Shrewsbury, New Jersey http://counter.li.org
^^-^^ 10:10:01 up 7 days, 11:37, 3 users, load average: 4.39, 4.29, 4.22
.