device polling and weird timer interrupt count from vmstat

[Nikos Vassiliadis]

On Monday 24 September 2007 20:58, Artem Kuchin wrote:
> > What i don't understand is why timer rate on each cpu is 1995? I have
> > set it to 1000, not 1995 or 2000. I have seen it showing 2000 on
> > another box.
> > So
> > 1) why not 1000?

<DOUBLING>
I can only make assumptions about the doubling, and I don't want to.
FreeBSD is not a RTOS and some milliseconds variation is understandable.

> > 2) if it is supposed to be doubled (why?) when why not 2000?

I can only make assumptions about the doubling, and I don't want to.
FreeBSD is not a RTOS and some milliseconds variation is understandable.
</DOUBLING>

> > 3) Is timer int really generated on each cpu?

Apparently, why do you doubt it?

> > Am i really wasting cpu 
> > time on ~4000 ints per second?

You can lower it you know, if you feel that you are waisting
that much resources. Ofcourse you'll break your traffic flow
that way, since latency will increase.

You seem very upset about it, are you sure you want to use
polling(4)? it uses much more resources than interrupts.

> > 4) does twe driver use polling? whay about twa? how to check it in
> > the sources?

Polling is only used on some network interface drivers. Polling(4)
does not offer generic device-polling facilities.

By the way, you know your post has an aggressive sense, don't you?
Please don't do this when asking questions and want replies.
Such technical comments are not useful to anybody.

HTH

Nikos