Top not showing cpu usage even remotely accurately

[Giorgos Keramidas]

On 2006-08-10 00:45, "Tamouh H." <hakmi at rogers.com> wrote:
> > But since running 5.x (5.5-STABLE since 1st Aug) top can show 
> > 0.0% idle but the cpu usages shown don't add up to much of a 
> > fraction of 100%.

In recent 6.X versions, you can use 'S' to show system threads too.
For an even more fine-grained view, you can use 'H' to show each
thread separately.

Then there is also the 'CPU' mode (as opposed to the default 'WCPU'
mode of top).

> I've the same issue with FBSD 5.4 and TOP. In fact, the load
> averages are so irrelevant now that I barely pay attention to
> them. The server goes to 4 or 6 load averages without slowing down,
> and other times the load average would be 0.8 and the server is
> running slow.

Probably because the work it does at the moment is not CPU-bounded?

> An example of unmatching TOP:
> 
> last pid: 17889;  load averages:  0.60,  0.52,  0.50                                                  up 3+17:22:33  00:41:45
> 186 processes: 2 running, 183 sleeping, 1 lock
> CPU states: 30.0% user,  0.0% nice,  1.7% system,  0.1% interrupt, 68.3% idle
> Mem: 1678M Active, 1110M Inact, 287M Wired, 87M Cache, 112M Buf, 103M Free
> Swap: 8762M Total, 1584K Used, 8760M Free
> 
>   PID USERNAME PRI NICE   SIZE    RES STATE  C   TIME   WCPU    CPU COMMAND
>  5071 nobody   101    0 43124K 35180K CPU2   2   0:07 14.89% 14.89% httpd
> 14409 nobody     4    0 43940K 36076K sbwait 0   0:01  1.22%  1.22% httpd
> 95515 nobody     4    0 39892K 32188K sbwait 1   0:08  0.29%  0.29% httpd

Try hitting 'S'.  Perhaps the system spends too much time in system
threads (i.e. the "syncer") :)