incorrect ping(8) interval with powerd(8)

[M. Warner Losh]

In message: <20050616075743.GE2239 at obiwan.tataz.chchile.org>
            Jeremie Le Hen <jeremie at le-hen.org> writes:
: > : May you delve into this a little bit more please ?  The ping(8) manual
: > : page states that the -i flags makes ping(8) to wait a given couple of
: > : seconds.  If I use the flags "-i 1", I expect ECHO Requests to be sent
: > : with one second between each, whatever the AC line status is.
: > : (Note that I didn't explicitely specified "-i 1" in the above example,
: > : but this doesn't change the behaviour.)
: > 
: > Well, the rount trip times went way up (3x longer).  That's normal for
: > a 200MHz CPU...  My 333MHz EISA machine can't do much better than
: > that.
: > 
: > But the 2.252s run time is a little longish.  Do you see this
: > consistantly?  If you ran it a second time would you get identical
: > results.  I've seen ARP take a while...  What else do you have running
: > on the system?  Maybe a daemon that takes almost no time at 1.7GHz
: > takes a lot longer at 200Mhz and that's starving the ping process...
: > Or some driver has gone insane...
: 
: Yes, I ran this test multiple times, and I almost get always this same
: result although I got 2.208s sometimes, but I don't think this is
: significant.
: 
: FYI,
: my powerd(8) is configured to tastes AC-line four times per seconds.
: I tried reducing it's freqency from 4 to 1, but it doesn't change
: anything.
: 
: ARP is not the culprit, the MAC address is already in cache.
: 
: My kernel is compiled with INVARIANTS, but I don't have WITNESS.  My
: network interface uses the bge(4) driver.  No firewall rule or complex
: network setup.
: 
: Anyway this doesn't hurt much.  Thanks for lightening me.

Dang, I was hoping it was one of the easy explainations....  Maybe it
is the idle code not waking up fast enough when it has been asleep for
a bit.  But that's pure speculation at this point...

Warner