dummynet(4) kernel process CPU usage monitoring

[Eugene Grosbein]

21.11.2011 23:37, Ryan Stone пишет:
> On Mon, Nov 21, 2011 at 1:23 AM, Eugene Grosbein <eugen at grosbein.pp.ru> wrote:
>> Hi!
>>
>> I need to draw graph of dummynet's CPU usage.
>> "procstat -t 0" shows me TID (thread id) of dummynet kernel thread.
>> "ps -Hxo time,lwp" shows me total CPU time consumed by this thread.
>>
>> Now I see this time has 9 seconds increase during 60 seconds of real time.
>> This should be 9/60=15% CPU usage, but "top -SHP" shows me 0.00% meantime.
>>
>> Where is my error?

> Which version are you running?  8.1-RELEASE and older have the problem
> that the scheduler and the CPU statistics gatherer are driven from the
> same clock.  For threads that tend to frequently wake up and run for
> less than a full tick(dummynet would appear to fall in this category)
> this means that CPU usage statistics are never captured at a point
> where those threads are running, so top shows 0% for those threads.
> 
> I am told that some relatively recent timer-related work(eventtimer?)
> should have resolved the issue, which is definitely in 9.0 and might
> be in stable/8 and may even have made it into 8.2-RELEASE.

I run 8.2-STABLE of 16 October. During most busy hours top shows
some nonzero values but TIME obtained from ps(1) is still several times larger.

Eugene Grosbein