At 11:25 AM 12/1/2006, Steven M. Bellovin wrote:
> >
>I'd have expected the problem to show as drops on the output queue, not
>ipintrq, unless you're running at near-100% CPU.  The previous case did
>not involve CPU exhaustion -- does yours?

Hi,

I think it does in this case.  As I cannot interact with the box at 
the time of testing its hard to tell.  But if I moderate the blast to 
a slower rate, top seems to indicate its approaching full utilization 
for interrupt processing.  I am using FreeBSD's 
/usr/src/tools/tools/netrate to generate the traffic.

At 100K, interrupt usage gets to 30%

load 
averages:  0.06,  0.08,  0.08 
                              up 0 days, 11:22   06:49:02
37 processes:  1 runnable, 35 sleeping, 1 on processor
CPU0 states:  0.0% user,  0.0% nice,  0.0% system, 28.3% interrupt, 71.7% idle
CPU1 states:  0.0% user,  0.0% nice,  0.0% system,  0.0% interrupt,  100% idle
Memory: 31M Act, 484K Wired, 4100K Exec, 5284K File, 1950M Free
Swap: 128M Total, 128M Free


200K

load 
averages:  0.13,  0.09,  0.08 
                              up 0 days, 11:23   06:50:06
38 processes:  1 runnable, 36 sleeping, 1 on processor
CPU0 states:  0.0% user,  0.0% nice,  0.0% system, 50.0% interrupt, 50.0% idle
CPU1 states:  0.0% user,  0.0% nice,  0.0% system,  0.0% interrupt,  100% idle
Memory: 31M Act, 484K Wired, 4100K Exec, 5300K File, 1950M Free
Swap: 128M Total, 128M Free

As it gets to 450Kpps, the box gets a little sluggish and difficult 
to interact with.


load 
averages:  0.15,  0.11,  0.09 
                              up 0 days, 11:26   06:53:19
38 processes:  1 runnable, 36 sleeping, 1 on processor
CPU0 states:  0.0% user,  0.0% nice,  0.0% system, 97.2% interrupt,  2.8% idle
CPU1 states:  0.0% user,  0.0% nice,  0.0% system,  0.0% interrupt,  100% idle
Memory: 31M Act, 484K Wired, 4100K Exec, 5300K File, 1950M Free
Swap: 128M Total, 128M Free