[asterisk-users] MeetMe() and dahdi_dummy on an embedded system

[Vinícius Fontes]

I'm playing around with an ALIX 2D2 board (http://www.pcengines.ch/alix2d2.htm). It's a fanless, x86 system using an AMD Geode processor with 256MB of RAM. Also available are two network interfaces, two USB ports and one serial port (no keyboard or VGA). I'm using the Voyage Linux distro, which basically is Debian Lenny optimized for this board.

Asterisk 1.6.1.12 runs fine on the system. The only issue I'm having is with MeetMe(). As there's no DAHDI devices attached, I'm running dahdi_dummy. Audio gets all choppy on MeetMe(), but works fine for other applications such as Playback(). SIP calls also work fine.

Most probably it's a timing issue. I connected an Astribank unit with 16 FXS in order to provide timing, and after that I get crystal clear audio on MeetMe().

Of course I wouldn't like to have an expensive Astribank attached to the ALIX board just to provide timing. So my question is: is there any way to improve dahdi_dummy's performance, or maybe some other way to get this to work without the need for a physical DAHDI device?

By the way, I have already tried to set internal_timing=yes on asterisk.conf, nothing changed.

Here's some relevant info on the system:

voyage:~# cat /proc/interrupts 
           CPU0       
  0:         23    XT-PIC-XT        timer
  2:          0    XT-PIC-XT        cascade
  3:          1    XT-PIC-XT      
  4:        255    XT-PIC-XT        serial
  7:    9090731    XT-PIC-XT        mfgpt-timer
 10:     166087    XT-PIC-XT        eth0
 12:    1110139    XT-PIC-XT        ehci_hcd:usb1, ohci_hcd:usb2
 14:      14638    XT-PIC-XT        ide0
NMI:          0   Non-maskable interrupts
LOC:          0   Local timer interrupts
SPU:          0   Spurious interrupts
ERR:          0
MIS:          0

voyage:~# cat /proc/cpuinfo 
processor	: 0
vendor_id	: AuthenticAMD
cpu family	: 5
model		: 10
model name	: Geode(TM) Integrated Processor by AMD PCS
stepping	: 2
cpu MHz		: 498.070
cache size	: 128 KB
fdiv_bug	: no
hlt_bug		: no
f00f_bug	: no
coma_bug	: no
fpu		: yes
fpu_exception	: yes
cpuid level	: 1
wp		: yes
flags		: fpu de pse tsc msr cx8 sep pge cmov clflush mmx mmxext 3dnowext 3dnow
bogomips	: 996.14
clflush size	: 32
power management:

voyage*CLI> timing test 
Attempting to test a timer with 50 ticks per second.
Using the 'DAHDI' timing module for this test.
It has been 1000 milliseconds, and we got 50 timer ticks

voyage:~# dahdi_test -vv
Opened pseudo dahdi interface, measuring accuracy...

8192 samples in 8192.000 system clock sample intervals (100.000%)
8192 samples in 8192.000 system clock sample intervals (100.000%)
8192 samples in 8192.000 system clock sample intervals (100.000%)
8192 samples in 8192.000 system clock sample intervals (100.000%)
8192 samples in 8192.000 system clock sample intervals (100.000%)
8192 samples in 8192.000 system clock sample intervals (100.000%)
8192 samples in 8192.000 system clock sample intervals (100.000%)
8192 samples in 8192.000 system clock sample intervals (100.000%)
8192 samples in 8192.000 system clock sample intervals (100.000%)
8192 samples in 8192.000 system clock sample intervals (100.000%)
8192 samples in 8192.000 system clock sample intervals (100.000%)
8192 samples in 8192.000 system clock sample intervals (100.000%)
8192 samples in 8192.000 system clock sample intervals (100.000%)
8192 samples in 8192.000 system clock sample intervals (100.000%)
8192 samples in 8192.000 system clock sample intervals (100.000%)
8192 samples in 8192.000 system clock sample intervals (100.000%)
8192 samples in 8192.000 system clock sample intervals (100.000%)
8192 samples in 8192.000 system clock sample intervals (100.000%)
8192 samples in 8192.000 system clock sample intervals (100.000%)
8192 samples in 8192.000 system clock sample intervals (100.000%)
8192 samples in 8192.000 system clock sample intervals (100.000%)^C
--- Results after 21 passes ---
Best: 100.000 -- Worst: 100.000 -- Average: 100.000000, Difference: 100.000000


Atenciosamente,

Vinícius Fontes
Gerente de Segurança da Informação
Canall Tecnologia em Comunicações
Passo Fundo - RS - Brasil
+55 54 2104-7000

Information Security Manager
Canall Tecnologia em Comunicações
Passo Fundo - RS - Brazil
+55 54 2104-7000