horrible zttest results.

[stuck]

Recently, prompted by the call quality issues and occasional call drops or audio loss, I started looking into various causes of my system performance. I came across some posts talking about IRQ conflicts and zttest timing performance.

So I started taking a closer look at my systems none of them have any FXS/FXO cards. As I suspect, they all have some degree of IRQ sharing (from lspci -vb command). I've got about 3-4 system. All are sharing USB with either the onboard VGA or onboard ethernet, or VGA sharing with Ethernet and IDE interface. They are all former Dell desktops or server's with P4 2.4-3.0ghz CPU and ~1gig of ram. 3 of the systems run updated Piaf 1.1 the other system run Piaf 1.2

Worse yet, all of them have zttest results that are horrendous, average of 99.954
Looking in the MB Bios doesn't give me options to move those conflicting IRQ's.
What other options should I look at to improve those zttest results?

Joe,
you said in one of your posts that ztdummy uses USB for timing... is that still true in Piaf? all of my systems are running kernel 2.6.18 which I thought does not use the USB for timing? If that's the case, I wonder if disabling USB would help?

 

[jroper]

Hi

Asterisk needs a timing source to do conferencing and som other stuff. Normally it would take timing from an installed card such as a Digium TDM400 etc.

If no card is present in the system, then it uses USB and ztdummy for a timing source.

Thus, if you have a telephony card in the machine, you can safely disable USB.

Joe

 

[stuck]

Hi Joe,
I don't mean to disagree with you. But this is where I read that stuff on ztdummy timing source for kernel 2.6, and I just want to get clarification on our Piaf system.
http://www.voip-info.org/wiki-Asterisk+timer+ztdummy

"For Linux kernel version 2.4 the ztdummy module takes timing from the usb-uhci kernel module, which should be loaded before ztdummy. Note that usb-uhci must not be compiled into the kernel, it'll only work with ztdummy if loaded as a module! On kernel version 2.6 ztdummy uses internal high-resolution kernel timer and does not require any USB. Using the internal kernel timer is recommended."

 

[stuck]

Well, I put in a FXO card, TDM400, into one of the machines that average 99.954% and immediately got 99.997%. I guess that builtin timing kernel is not that great.