Benchmarks

[Ingo Molnar]

* William Lovaton <williama_lovaton at coomeva.com.co> wrote:

> Load average is a good number to look at.  The thing is that a 1.5 load
> means there are almost 2 processes in execution state. [...]

the load also includes processes in 'uninterruptible sleep' - i.e. 
processes that are waiting for some sort of definitive, driver-related
IO event, such as disk IO or network IO.

Newer kernels (2.6, or vendor kernels with the 'iowait patch'
backported) also have the iowait stat:

 05:17:02  up 1 day, 21:43, 15 users,  load average: 0.61, 0.25, 0.19
74 processes: 72 sleeping, 2 running, 0 zombie, 0 stopped
CPU states:  cpu    user    nice  system    irq  softirq  iowait    idle
           total    3.4%    0.0%    5.2%   0.0%     0.0%   10.0%   81.4%

('softirq' overhead is typically caused by networking overhead, 'iowait'
is idle time while there is pending network/disk IO, and 'idle' is pure
idle time when nothing happens in the system.)

> > > > Machine is pushing 25.34mb/sec
> > > How do you get this number??  (25.34mb/sec)
> > right off the switch port.
> 
> Neat!  I'll talk with the net guy here.  ;-)

there are soft stats on the Linux side too:

	sar -n DEV 10 0

will display summary per-interface tx/rx statistics every 10 seconds. 

Also, 'iptraf' is a pretty handy tool too, for simple traffic analysis.

	Ingo