[asterisk-dev] Zaptel Interrupt Issues

[Matthew Fredrickson]

Bob wrote:
> I was reading all the #ifdefs incorrectly and assuming that the buffers in
> zaptel were for the PPP and NET. It's pretty hairy in there.
> 
> I do have some Wanpipe machines for testing. The PCI hardware is mostly
> irrelevant here. They all call zt_recieve and zt_tranmit 1000 times per
> second. Oddly enough ... Wanpipe hardware generates an rx and a tx
> interrupt, so it generates 2000 interrupts per second. Wanpipe also does a
> TON of data movement in the usual places around the two zaptel calls. It
> really affects their time in ISR very little.
> 
> In order to change the chunksize variable I had to use older cards for my
> testing. These cards all have the old Tigerjet syle DMA in them. That means
> that when I made the chunksize 512, all three of these drivers were moving
> 512 frames x 24 channels into the channel arrays in the interrupt context.
> (512 * 24 * 2 (tx/rx) = 24576 data moves) This didn't come anywhere close to
> doubling the time spent in the ISR. What I wound up with was a phone call
> that sounded like RTP, but it was just to prove a point.
> 
> Whether I am covering up for other driver's kernel time, or just reducing
> the context switching overhead seem irrelevant. Increasing the chunksize
> drastically improves data integrity under heavy load. 

That makes sense.  The increase in chunksize does indeed increase your 
ability to work around other drivers misdemeanors.

Matthew Fredrickson

> 
> As previous threads on this topic have mentioned, there are much higher data
> rate interfaces that don't have the same problem.
> 
> -----Original Message-----
> From: asterisk-dev-bounces at lists.digium.com
> [mailto:asterisk-dev-bounces at lists.digium.com] On Behalf Of Eric "ManxPower"
> Wieling
> Sent: Tuesday, October 02, 2007 1:08 PM
> To: Asterisk Developers Mailing List
> Subject: Re: [asterisk-dev] Zaptel Interrupt Issues
> 
> I'll bet his Zaptel has been patched by the Sangoma Wanpipe stuff.
> 
> 
> 
> 
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-- 
Matthew Fredrickson
Software/Firmware Engineer
Digium, Inc.