Device polling performance

TM4525 at TM4525 at
Sat Sep 25 08:40:28 PDT 2004

In a message dated 9/25/04 10:17:27 AM Eastern Daylight Time, mike at 
At 09:57 AM 25/09/2004, TM4525 at wrote:
>     As long as all your interfaces support polling, you should see
>hardly see any interrupt usage at all, as that is the whole point of
>polling.  You can allocate more or less CPU cycles to flinging packets
>around via various sysctl settings.  See the polling man pages for
>more info
>     ---Mike
>Thanks, but that doesn't answer the question. Since polling cycles don't 
>seem to be shown under any usage category, how do you know what your 
>system usage is when polling is enabled? It seems like a big negative to me.

Read the MAN page.  There is a whole section there on a number of MIB 
variables that display various statistics around polling.  50% of the CPU 
cycles are allocated to the system by default.  If that 50% is used up, it 
will show up in top under system processes in top.

Given a decent CPU, you wont see very much of a load average at all in the 
200Kpps / 100Mb range.


Ah, so the capacity of a FreeBSD router is > 10 million packets per second, 
since 200K pps only uses .1 % of system resources. Kudos to the FreeBSD team 
for developing a stack that uses no resources. 

It seems beyond unreasonable that, with interrupts enabled, 55% of the system 
is used, and with polling, ~ zero.

Since its clear you have no idea what you're talking about, perhaps if 
someone who actually does would like to pipe in it would be useful.

It seems obvious that the "system" resource is not accurately monitored with 
polling enabled,  which is what Im trying to get someone to admit, or to tell 
me when it was or will be repaired.


PS: and please dont tell me to read the man page again. 

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