asterisk users - Jun 2010 - Internal timing bad for Fax?

Hello, i just made the reproducible watching:
I send a Fax from asterisk (trunk) with spandsp (latest snapshot) via
T.38 -> Audiocodes Mediant 2000 (FW 5.60.43.5) -> PSTN Fax
With Internal timing Enabled, the Fax break after the first quarter
from the first page is transfered.
With Internal timing Disabled, the fax is transferred flawless.

Both test with pthread timing module on a QEMU Virtual maschine

So, is internal timing bad for Fax?

Kristijan

On 06/22/2010 12:24 PM, Kristijan Vrban wrote:
> Hello, i just made the reproducible watching:
> I send a Fax from asterisk (trunk) with spandsp (latest snapshot) via
> T.38 -> Audiocodes Mediant 2000 (FW 5.60.43.5) -> PSTN Fax
> With Internal timing Enabled, the Fax break after the first quarter
> from the first page is transfered.
> With Internal timing Disabled, the fax is transferred flawless.
> 
> Both test with pthread timing module on a QEMU Virtual maschine
> 
> So, is internal timing bad for Fax?
No, but you've chosen a very bad combination to provide timing;
res_timing_pthread uses a great deal of CPU to do its job (much more
than the other options), and you are running in a virtual machine on top
of that. If you are running on Linux and can run a kernel that supports
res_timing_timerfd, you'll have better results, but running in a virtual
machine will always means that you are subject to random
scheduling-related problems.

-- 
Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
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