[Asterisk-Users] CPU spikes with wcfxs loaded

[Stephan Schiessling]

After reading your advice I replaced the Via chipset asus board 
(Sempron) by a
Intel chipset MSI board (Celeron). Compiled the same kernel (2.6.8.1) 
for new hardware,
compiled asterisk (in bristuff-0.0.2 distribution), spandsp.
Spandsp now works, before it doesn't !

vmstat 1 shows me, that I get almost everytime the same number of interrupts
(from 17034 to 17056)
procs -----------memory---------- ---swap-- -----io---- --system-- 
----cpu----
 r  b   swpd   free   buff          cache   si   so    bi    bo   
in          cs us sy id wa
 1  0      0  91388 104828 146100    0    0     0     0 17034   169  0  
0 100  0
 0  0      0  91388 104836 146100    0    0     0    12 17035   177  0  
0 100  0
 0  0      0  91388 104836 146100    0    0     0     0 17034   169  0  
0 100  0

Compared to my via chipset asus mainboard, the number of interrupts are 
the same like above,
except when the harddisc is active. Then it drops to about 16050. (bo!=0).
hdparm -u1 /dev/hda (on via chipset asus system) avoids this, so number 
of interrupts stay almost constant.
With that I got a little more of a fax page, before it failed.
Setting pci latency (on via chipset asus system) by
setpci -v -s XX:X.X latency_timer=00
also helped me a little, since as best result, I got almost 75 % of a 
fax page, before it failed.

But with all these tricks, I never got a whole page (or even a several 
pages fax).
Only by switching to the intel chipset mainboard the timing problem 
seems to be resolved.
Thank you very much Craig Guy, for your advice!

If more readers experience the same problems with VIA chipset mainboards 
only, we should add a warning to
http://www.voip-info.org/wiki-Asterisk+Hardware

Bye,

Stephan Schiessling

Craig Guy wrote:

>If you are using an Athlon then you might have a VIA chipset and apparently
>non-intel chipsets can have these sorts of interrupt problems (Via
>especially).  Try changing to an intel chipset motherboard.
>
>Craig
>
>----- Original Message ----- 
>From: "Michael Welter" <mike at introspect.com>
>To: "Asterisk Users Mailing List - Non-Commercial Discussion"
><asterisk-users at lists.digium.com>; <support at digium.com>
>Sent: Tuesday, December 14, 2004 5:57 AM
>Subject: [Asterisk-Users] CPU spikes with wcfxs loaded
>
>
>  
>
>>I need to reopen this discussion because it's impossible to run spandsp
>>(and VoIP) under these circumstances.
>>
>>With zaptel unloaded, I see the following "vmstat 1" output:
>>
>>no swapping, an occasional disk output, +/- 1003 interrupts/sec., less
>>than 10 context switches/sec., CPU idle 100%.  A very quiet system.
>>
>>I load modules zaptel and wcfxo, and the system utilization stays the
>>same.  When I load wcfxs, the number of interrupts goes up to +-2004,
>>which is normal.  However, every three seconds the CPU spikes to 50%.
>>This is "system" utilization, not userland.  I assume it's in a wcfxs
>>interrupt.
>>
>>The number of interrupts stays constant at about 2004 during each spike,
>>leading me to the conclusion that the TDM card is holding an interrupt
>>for 500ms every three seconds (50% of 1000ms is 500ms).  This is a
>>disaster for spandsp and VoIP in general.
>>
>>When I unload the wcfxs module, CPU idle goes back to a constant 100%.
>>
>>The TDM22B card is REV E/F, and I've tried it with several different
>>cards.  Fedora Core 3 with linux-2.6.9 downloaded from kernel.org (a
>>stock kernel).  The CPU is Athlon K7.
>>
>>Can anyone please give me a clue?
>>
>>Thanks,
>>
>>-- 
>>Michael Welter
>>Introspect Telephony Corp.
>>Denver, Colorado US
>>+1.303.674.2575
>>mike at introspect.com
>>www.introspect.com
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>>    
>>
>
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