[Freeswitch-users] Call quality assurance

Stanislav Sinyagin ssinyagin at gmail.com
Fri Jun 5 02:23:51 MSD 2015

Michael, as far as I understand it, it works as follows:

timerfd is a kernel's means of providing the system clock to the
userland process (freeswitch daemon in our case).

The kernel takes the clock from one of available sources, and these
sources are either physical or software clocks:

# cat /sys/devices/system/clocksource/clocksource0/available_clocksource
tsc hpet acpi_pm
# cat /sys/devices/system/clocksource/clocksource0/current_clocksource

So, TSC was giving stable results, while HPET, although expected to be
more precise, was generating errors while the CPU was busy with other

On Thu, Jun 4, 2015 at 9:05 PM, Michael Jerris <mike at jerris.com> wrote:
> timerfd would be the preferred timing source on any remotely modern linux kernel
>> On Jun 4, 2015, at 6:47 AM, Stanislav Sinyagin <ssinyagin at gmail.com> wrote:
>> I summarized some experience gained in a customer project, hopefully
>> it will be useful:
>> https://txlab.wordpress.com/2015/06/02/quality-assurance-for-voip-calls-2/
>> @Anthony, you suggested to use HPET timer for better precision, but it
>> appears that it is affected by the CPU load: while the debian package
>> build script was running, the quality of recorded calls has degraded
>> -- even that the recording was done onto a TMPFS partition. With the
>> default TSC timer, this was not the case.
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