[Asterisk-Users] te110p and interrupts

[Anton Krall]

Hi Andrew... 

Thank you very much for the info.

I didn't recompile the kernel, Im using a generic 2.6 kernel but its worth
taking a look at what you said.. Where can I find (which file) the Hz the
kernel was precompiled to?

Also, Im running 1 te110p and 2 tdm cards, probably I'll disable 1 card
later but I will need at least 1 tdm and the te110p for my E1. 

So you suggest not disabling any apic/acpi stuff then.. How about HT? should
I disable that on the bios?

Im using supermicro servers and eventhough I get voice calls without
problems, Im getting a few IRQ Misses from time to time which makes faxing
on the E1 very difficult (the original problem).

What do you think?
 

|-----Original Message-----
|From: asterisk-users-bounces at lists.digium.com 
|[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of 
|Andrew Kohlsmith
|Sent: Tuesday, April 11, 2006 7:37 AM
|To: asterisk-users at lists.digium.com
|Subject: Re: [Asterisk-Users] te110p and interrupts
|
|On Monday 10 April 2006 19:20, Mojo with Horan & Company, LLC wrote:
|> Try booting with apic off, I think it's noapic kernel 
|option.  Notice 
|> this is "APIC" and not "ACPI", which you referred to.  Then get your 
|> boards on different REAL irqs.
|
|Please do not open your mouth to spout nonsense if you do not 
|know what you're talking about.
|
|APIC interrupts are far more "real" than emulated XT-PIC 
|interrupts.  If the IO-APIC can put each device on its own 
|"high" interrupt it means that that INT# signal on the PCI 
|slot *is* on a totally separate, physical IRQ line which is 
|routed into that APIC.  When you disable native APIC mode you 
|force it into compatibility mode, where it essentially 
|performs a logical "OR" on the real, separate IRQ lines and 
|gives you a single, edge-triggered i8259-style "low" IRQ.
|
|(In reality it's not a logical OR since the XT (i8259-style) 
|interrupts are edge-triggered, not level triggered, but that's 
|neither here nor there for this particular discussion.)
|
|Again, if the IO-APIC is reporting that the card is on its own 
|IRQ, it really, truly, honestly *IS* on its own IRQ.  The 
|reason that it is suggested to disable the IO-APIC is that on 
|many low-end systems, the IO-APIC is plain old broken and 
|causing other issues.  I don't think I've run across a system 
|board in the last year or two with that issue, though.  It's 
|always been on older P3 and early P4 systems.
|
|Anton, your problem is very likely simple interrupt load.  You 
|have three Digium cards in there, and they're all generating 
|their own 1000Hz interrupt.  
|If you did the newbie thing and compiled your kernel with a HZ 
|value of '1000' because you felt it would be better, you have 
|that overhead as well.
|
|Your system is very likely just having trouble coping with so 
|many interrupts.  
|My personal opinion is that you should sell the three Digium 
|cards and buy a single dualspan card and a cheap channel bank. 
| Your interrupt load will drop by 2/3 and your system will be 
|FAR happier.
|
|So check the kernel HZ value first; I set *all* my Asterisk 
|systems to the old style HZ of 100; there is simply no need 
|for anything more on a server,
|*especially* if you've already got hardware providing a real 
|1000Hz interrupt instead of ztdummy trying to emulate such a thing.
|
|-A.
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