[Freeswitch-users] KVM vs. XEN virtualization
Sergey Safarov
s.safarov at gmail.com
Sun Apr 12 22:02:33 MSD 2015
Key "-q" is recommended also. ;o)
On Sun, Apr 12, 2015 at 9:01 PM, Sergey Safarov <s.safarov at gmail.com> wrote:
> 1) But in your case, cyclictest can generate 336000 (42*8000) hardware
> timer irqs per second VS 8000 from TDM card's.
>
> Very interest results.
> My example creates a lot of unnecessary interruptions
> For VoIP only host more correctly measured so
> cyclictest -t42 -p -d 80 0 -n -i -l 5000 6000
> or
> cyclictest -t42 -p -d 80 0 -n -i -l 10000 3000
>
> If FS has one TDM cards then
> cyclictest -t1 -p -d 80 0 -n -i -l 125 240000
>
> If two TDM cards
> cyclictest -t2 -p -d 80 0 -n -i -l 125 240000
>
> Where "-t" key equal number of TDM cards
>
> 2) According to Digium sources your TDM card have 20ms max buffer size(3ms
> default)
> USB dongles have at least 20 ms.
>
> Can you describe how you have found this information. It is very interest.
>
> Sergey
>
>
> On Fri, Apr 10, 2015 at 5:06 PM, Dmitry Lysenko <dvl36.ripe.nick at gmail.com
> > wrote:
>
>> 2015-04-10 0:33 GMT+03:00 Sergey Safarov <s.safarov at gmail.com>:
>>
>>> 1) Most(if not all) of modern equipment have buffers. TDM cards too.
>>> Even $0.25 microcontrollers have buffers.
>>> Firing interrupts at each PCM sample not needed.
>>>
>>> The problem is whether there is or not the buffer. Is exist in all the
>>> equipment.
>>> The problem is the amount of buffer, and through any time it overflows.
>>> I thing you cannot say buffer size has TDM card and USB modems. :o)
>>>
>>
>> According to Digium sources your TDM card have 20ms max buffer size(3ms
>> default)
>> USB dongles have at least 20 ms.
>>
>>
>>> The above i write results of testing Digium E1 card in virtual
>>> environment. Test that is successful on real host, will fail in virtual
>>> environment.
>>> I you see source of timertest utility you will see that Digium test
>>> timer for 8000 samples for 1000 ms (1s). (Primary utility author Mark
>>> Spencer <markster at digium.com>)
>>> It is same value I recommend early.
>>>
>>
>> But in your case, cyclictest can generate 336000 (42*8000) hardware timer
>> irqs per second VS 8000 from TDM card's.
>>
>> Look:
>> root at debian:~# vmstat 1
>> procs -----------memory---------- ---swap-- -----io---- -system--
>> ----cpu----
>> r b swpd free buff cache si so bi bo in cs us sy
>> id wa
>> 0 0 0 2348 85428 21156 0 0 134 0 1856 3409 1 2
>> 92 5
>> 0 0 0 2320 85428 21156 0 0 0 0 106 224 1 0
>> 99 0
>> [similar, skipped]
>> 0 0 0 2312 85436 21156 0 0 0 0 110 231 0 0
>> 100 0
>> 0 0 0 2312 85436 21156 0 0 0 0 109 225 0 2
>> 98 0
>> 45 0 0 1924 84908 21156 0 0 0 0 102909 146412 0
>> 60 39 0
>> Starting of cyclictest with your parameters ^^^^^.
>>
>> 102909 interrupts and 146412 context switches per second.
>> For one TDM card there should be slightly more then 8000 of interrupts.
>>
>> Results:
>>
>> root at debian:~/rt-tests# ./cyclictest -t42 -p 80 *-d 0* -n -i 125 -l
>> 240000 -q
>> WARN: stat /dev/cpu_dma_latency failed: No such file or directory
>> T: 0 ( 4028) P:80 I:125 C: 239821 Min: 0 Act:100534 Avg:38764 Max:
>> 229794
>> T: 1 ( 4029) P:80 I:125 C: 239820 Min: 0 Act:100536 Avg:39646 Max:
>> 233558
>> T: 2 ( 4030) P:80 I:125 C: 240000 Min: 0 Act:100478 Avg:37947 Max:
>> 229143
>> T: 3 ( 4031) P:80 I:125 C: 240000 Min: 0 Act:106202 Avg:38130 Max:
>> 239031
>> [similar,skipped]
>> T:38 ( 4066) P:80 I:125 C: 239821 Min: 1 Act:100292 Avg:41273 Max:
>> 238424
>> T:39 ( 4067) P:80 I:125 C: 239822 Min: 0 Act:100174 Avg:40254 Max:
>> 238881
>> T:40 ( 4068) P:80 I:125 C: 239816 Min: 0 Act:100650 Avg:39910 Max:
>> 239104
>> T:41 ( 4069) P:80 I:125 C: 239817 Min: 0 Act:100526 Avg:38282 Max:
>> 224452
>> root at debian:~/rt-tests#
>>
>> Increased intervals between threads:
>>
>> root at debian:~/rt-tests# ./cyclictest -t42 -p 80 *-d 40* -n -i 125 -l
>> 240000 -q
>> WARN: stat /dev/cpu_dma_latency failed: No such file or directory
>> T: 0 ( 4203) P:80 I:125 C: 240000 Min: 1 Act: 35 Avg: 28 Max:
>> 159
>> T: 1 ( 4204) P:80 I:165 C: 181909 Min: 6 Act: 47 Avg: 29 Max:
>> 170
>> T: 2 ( 4205) P:80 I:205 C: 146417 Min: 6 Act: 15 Avg: 29 Max:
>> 157
>> T: 3 ( 4206) P:80 I:245 C: 122512 Min: 6 Act: 33 Avg: 30 Max:
>> 166
>> [similar,skipped]
>> T:38 ( 4241) P:80 I:1645 C: 18246 Min: 7 Act: 27 Avg: 34 Max:
>> 167
>> T:39 ( 4242) P:80 I:1685 C: 17813 Min: 8 Act: 13 Avg: 34 Max:
>> 164
>> T:40 ( 4243) P:80 I:1725 C: 17398 Min: 7 Act: 22 Avg: 33 Max:
>> 156
>> T:41 ( 4244) P:80 I:1765 C: 17004 Min: 8 Act: 49 Avg: 34 Max:
>> 141
>> root at debian:~/rt-tests#
>>
>> Huge difference, isn't it?
>>
>> 2) If you want massive sync audio processing (w/o buffering) you can use
>>> hard realtime OS. PC and Linux (even on bare metal) is not suitable for
>>> this, at least without RT patched kernel.
>>>
>>> I am not understanding about you speaking. E1 card can be used on real
>>> host without problems.
>>>
>>
>> They use buffering. Delays of 125uS is not uncommon in ordinary Linux
>> kernel. BTW, google "system management interrupt".
>>
>> 3) AFAIR, 1 thread per call leg, but depends of endpoints. Most of time
>>> threads in I/O waiting/sleeping and encoding/decoding state.
>>>
>>> One thread per FS call, equal one thread cyclictest. In cyclictest most
>>> time threads sleep also. This threads measure time interval and sleep again.
>>>
>>
>> In Freeswitch all of threads are not waking up every 125uS synchronously.
>> .And TDM cards are not generating tens/hundreds of thousands interrupts per
>> second as cyclictest can do.
>>
>> IMO, to simulate something like 1 TDM E1 card using cyclictest you should
>> use parameters that give you additional ~8000 irqs.
>>
>> root at debian:~# vmstat 1
>> procs -----------memory---------- ---swap-- -----io---- -system--
>> ----cpu----
>> r b swpd free buff cache si so bi bo in cs us sy
>> id wa
>> 0 0 0 3496 84304 21156 0 0 45 0 999 562 1 1
>> 97 2
>> 0 0 0 3496 84304 21156 0 0 0 0 105 222 0 0
>> 100 0
>> 0 0 0 2784 84304 21156 0 0 0 0 4276 8482 2 15
>> 83 0
>> 0 0 0 2784 84304 21156 0 0 0 0 8705 17146 2 35
>> 63 0
>> 0 0 0 2784 84304 21156 0 0 0 0 8678 17099 3 33
>> 64 0
>> 0 0 0 2784 84304 21156 0 0 0 0 8707 17135 2 37
>> 61 0
>>
>> In my case additional 8000 irqs with these parameters:
>>
>> root at debian:~/rt-tests# ./cyclictest -t 30 -p 80 -d 30 -n -i 3000 -l
>> 24000 -q
>> WARN: stat /dev/cpu_dma_latency failed: No such file or directory
>> T: 0 ( 5862) P:80 I:3000 C: 24000 Min: 7 Act: 9 Avg: 9 Max:
>> 33
>> T: 1 ( 5863) P:80 I:3030 C: 23767 Min: 6 Act: 17 Avg: 8 Max:
>> 49
>> T: 2 ( 5864) P:80 I:3060 C: 23534 Min: 6 Act: 12 Avg: 8 Max:
>> 45
>> [same,skipped]
>> T:26 ( 5888) P:80 I:3780 C: 19051 Min: 7 Act: 8 Avg: 9 Max:
>> 35
>> T:27 ( 5889) P:80 I:3810 C: 18901 Min: 7 Act: 11 Avg: 8 Max:
>> 40
>> T:28 ( 5890) P:80 I:3840 C: 18754 Min: 7 Act: 14 Avg: 8 Max:
>> 39
>> T:29 ( 5891) P:80 I:3870 C: 18608 Min: 7 Act: 14 Avg: 8 Max:
>> 36
>>
>>
>>> 6) In your case, most capable realtime hypervisor with RT_PREEMPT guest
>>> would be one of the best solution.
>>>
>>> May be. According this publication (
>>> http://www.linux-kvm.org/wiki/images/0/03/KVM-Forum-2011-RT-KVM.pdf)
>>> guest threads can be interrupted not more 112 uS.
>>>
>>> Simple solution - for TDM card enough ordinary processor without
>>> virtualization. :o)
>>>
>>
>> This is a best solution.
>>
>>
>>> On Thu, Apr 9, 2015 at 8:09 PM, Dmitry Lysenko <
>>> dvl36.ripe.nick at gmail.com> wrote:
>>>
>>>>
>>>>
>>>> 2015-04-08 15:25 GMT+03:00 Sergey Safarov <s.safarov at gmail.com>:
>>>>
>>>>> 1) 125uS is the interval between FrameSync of ONE(!) PCM sample at
>>>>> 8000hz,
>>>>> But here we are talking about packet telephony where commonly used
>>>>> frame length is 20000 uS.
>>>>> So, intervals for testing should be 5000-10000-20000uS, not 125uS.
>>>>>
>>>>> Not all FS installation has SIP endpoint. Some can have TDM cards, USB
>>>>> dongle and other analog equipment. Can you say what is length of this frame
>>>>> type?
>>>>> I am wondering about this question. I know that the frame 125ms is
>>>>> enough.
>>>>>
>>>>
>>>> Most(if not all) of modern equipment have buffers. TDM cards too. Even
>>>> $0.25 microcontrollers have buffers.
>>>> Firing interrupts at each PCM sample not needed.
>>>> If you want massive sync audio processing (w/o buffering) you can use
>>>> hard realtime OS. PC and Linux (even on bare metal) is not suitable for
>>>> this, at least without RT patched kernel.
>>>>
>>>>
>>>>> 2) Why you decided that all of 42 threads should wake up
>>>>> simultaneously?
>>>>> That totally impossible in real world applications.
>>>>> Here should be tens of uS. Dependent of network card and, possibly,
>>>>> other I/O hardware.
>>>>>
>>>>> Can you say how many FS create threads for 40-50 active calls?
>>>>>
>>>>
>>>>
>>>> AFAIR, 1 thread per call leg, but depends of endpoints. Most of time
>>>> threads in I/O waiting/sleeping and encoding/decoding state.
>>>>
>>>>
>>>>> 3) -q switch is missing
>>>>> I am thinking it is optional. Result is same
>>>>>
>>>>
>>>> Dynamic output to screen consumes resources. How much, depends on
>>>> method.(VGA, Serial console, SSH). In my case difference is significiant.
>>>> So, fair testing should exclude such things, IMO.
>>>>
>>>>
>>>>> 4) Precise time measurement and realtime processing in VM environment
>>>>> is a challenge.
>>>>> To obtain acceptable results fine tuning of host's and guest's
>>>>> required.
>>>>> WIthout that this numbers ... does not mean anything.
>>>>>
>>>>> Can you learn me how to correctly measure timer source quality in VM?
>>>>>
>>>>
>>>> Serious players, as Wind River, use external timer.
>>>>
>>>> In your case, most capable realtime hypervisor with RT_PREEMPT guest
>>>> would be one of the best solution.
>>>>
>>>> Dmitry.
>>>>
>>>>
>>>>> On Wed, Apr 8, 2015 at 2:07 PM, Dmitry Lysenko <
>>>>> dvl36.ripe.nick at gmail.com> wrote:
>>>>>
>>>>>> 2015-04-07 10:48 GMT+03:00 Sergey Safarov <s.safarov at gmail.com>:
>>>>>>
>>>>>>> ...
>>>>>>> 2) i 125 - time us between software timer interrupts for first
>>>>>>> thread. It time is equal time between samples rate in PSTN networks
>>>>>>> In order to maintain our sampling rate we have 125 microseconds (uS)
>>>>>>> between consecutive samples (1/8,000Hz), which is more
>>>>>>>
>>>>>> ...
>>>>>>>
>>>>>>
>>>>>> 125uS is the interval between FrameSync of ONE(!) PCM sample at
>>>>>> 8000hz,
>>>>>> But here we are talking about packet telephony where commonly used
>>>>>> frame length is 20000 uS.
>>>>>> So, intervals for testing should be 5000-10000-20000uS, not 125uS.
>>>>>>
>>>>>>
>>>>>>> 3) d 0 - this switch will make time between software timer
>>>>>>> interrupts for second and following threads is equal timer value for first
>>>>>>> thread
>>>>>>>
>>>>>>
>>>>>> Why you decided that all of 42 threads should wake up simultaneously?
>>>>>> That totally impossible in real world applications.
>>>>>> Here should be tens of uS. Dependent of network card and, possibly,
>>>>>> other I/O hardware.
>>>>>>
>>>>>>
>>>>>>> 4) l 240000 - how many timer test must be made. It is adjusted for
>>>>>>> 30 s overall test
>>>>>>> 5) n - use clock_nanosleep. it is allow take more accurate timer
>>>>>>> test values on my VM
>>>>>>> 6) p 80 - it is copied from example on Cyclictest page
>>>>>>>
>>>>>>
>>>>>> -q switch is missing.
>>>>>>
>>>>>>
>>>>>>> And how in your opinion this numbers are related to Freeswitch in VM
>>>>>>> environment?
>>>>>>> Relation between Cyclictest switches and FS described above.
>>>>>>> Relation betwen Cyclictest results and FS simple
>>>>>>>
>>>>>>
>>>>>> Precise time measurement and realtime processing in VM environment
>>>>>> is a challenge.
>>>>>> To obtain acceptable results fine tuning of host's and guest's
>>>>>> required.
>>>>>> WIthout that this numbers ... does not mean anything.
>>>>>>
>>>>>>
>>>>>> On Tue, Apr 7, 2015 at 5:38 AM, Dmitry Lysenko <
>>>>>>> dvl36.ripe.nick at gmail.com> wrote:
>>>>>>>
>>>>>>>> Sergey,
>>>>>>>> Why you suggest to use exactly this numbers in cyclictest's
>>>>>>>> switches?
>>>>>>>> And how in your opinion this numbers are related to Freeswitch in
>>>>>>>> VM environment?
>>>>>>>>
>>>>>>>> P.S.
>>>>>>>> https://mindlinux.wordpress.com/2013/10/25/using-and-understanding-the-real-time-cyclictest-benchmark-frank-rowand-sony/
>>>>>>>>
>>>>>>>> 2015-04-06 15:27 GMT+03:00 Sergey Safarov <s.safarov at gmail.com>:
>>>>>>>>
>>>>>>>>> Errol can you test VM timer with utility
>>>>>>>>> https://rt.wiki.kernel.org/index.php/Cyclictest
>>>>>>>>>
>>>>>>>>> My VM currently have folowing results
>>>>>>>>>
>>>>>>>>> [root at fs1 ~]# date && /tmp/rt-tests/cyclictest -t42 -p 80 -d 0 -n -i 125 -l 240000 && date
>>>>>>>>> Sun Apr 5 07:01:31 GMT 2015
>>>>>>>>> # /dev/cpu_dma_latency set to 0us
>>>>>>>>> policy: fifo: loadavg: 2.38 0.93 0.50 1/194 1574
>>>>>>>>>
>>>>>>>>> T: 0 ( 1531) P:80 I:125 C: 240000 Min: 2 Act: 12 Avg: 16 Max: 1302
>>>>>>>>> T: 1 ( 1532) P:80 I:125 C: 240000 Min: 2 Act: 15 Avg: 14 Max: 2895
>>>>>>>>> T: 2 ( 1533) P:80 I:125 C: 240000 Min: 3 Act: 10 Avg: 12 Max: 2888
>>>>>>>>> T: 3 ( 1534) P:80 I:125 C: 240000 Min: 1 Act: 16 Avg: 13 Max: 1333
>>>>>>>>> T: 4 ( 1535) P:80 I:125 C: 240000 Min: 2 Act: 20 Avg: 14 Max: 2962
>>>>>>>>> T: 5 ( 1536) P:80 I:125 C: 240000 Min: 1 Act: 12 Avg: 14 Max: 2946
>>>>>>>>> T: 6 ( 1537) P:80 I:125 C: 240000 Min: 2 Act: 10 Avg: 13 Max: 1363
>>>>>>>>> T: 7 ( 1538) P:80 I:125 C: 240000 Min: 2 Act: 12 Avg: 13 Max: 1344
>>>>>>>>> T: 8 ( 1539) P:80 I:125 C: 240000 Min: 3 Act: 12 Avg: 16 Max: 1408
>>>>>>>>> T: 9 ( 1540) P:80 I:125 C: 240000 Min: 1 Act: 8 Avg: 13 Max: 2882
>>>>>>>>> T:10 ( 1541) P:80 I:125 C: 239974 Min: 2 Act: 12 Avg: 13 Max: 2908
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Mon, Apr 6, 2015 at 11:15 AM, Errol Samuels <
>>>>>>>>> ewsamuels at gmail.com> wrote:
>>>>>>>>>
>>>>>>>>>> Good job and Thanks for sharing!
>>>>>>>>>>
>>>>>>>>>> KVM at digitalocean.com, Debian 7 64bit, FreeSWITCH 1.4.15: bad
>>>>>>>>>>> precision
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> As someone who has been using KVM for a few years and has just
>>>>>>>>>> migrated about 20 VMs across to Digital Ocean about 6 weeks ago I admit I
>>>>>>>>>> am a little concerned about this finding.
>>>>>>>>>>
>>>>>>>>>> Just out of curiosity can you tell me the specs of the VM that
>>>>>>>>>> you tested with and which DO Datacenter? I am using NYC3 so perhaps and I
>>>>>>>>>> will do some tests as soon as I have some time.
>>>>>>>>>>
>>>>>>>>>> With regards to Xen was this at Linode or inhouse?
>>>>>>>>>>
>>>>>>>>>> Thanks
>>>>>>>>>>
>>>>>>>>>> Errol
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On Sun, Apr 5, 2015 at 1:37 AM, Stanislav Sinyagin <
>>>>>>>>>> ssinyagin at gmail.com> wrote:
>>>>>>>>>>
>>>>>>>>>>> here we go:
>>>>>>>>>>>
>>>>>>>>>>> https://txlab.wordpress.com/2015/04/05/testing-rtp-clock-precision-on-a-virtual-machine/
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> On Sat, Apr 4, 2015 at 4:26 PM, Stanislav Sinyagin <
>>>>>>>>>>> ssinyagin at gmail.com> wrote:
>>>>>>>>>>> > On Sat, Apr 4, 2015 at 1:03 PM, Regis M <
>>>>>>>>>>> regis.freeswitch.org at tornad.net> wrote:
>>>>>>>>>>> >> How do you check wavs together in audacity ?
>>>>>>>>>>> >
>>>>>>>>>>> > you just open two WAV files, align their starting position, and
>>>>>>>>>>> > visually check the waves. If there's a problem, you would see
>>>>>>>>>>> that
>>>>>>>>>>> > after few seconds, the waves are not aligned any more.
>>>>>>>>>>> >
>>>>>>>>>>> >> Can you send me 2 samples wav (send... and recorded) so I
>>>>>>>>>>> could see the 20ms
>>>>>>>>>>> >> diff that you exposed...
>>>>>>>>>>> >>
>>>>>>>>>>> >> Is there a way to automate the result checking, so it could
>>>>>>>>>>> help to monitor
>>>>>>>>>>> >> itsp quality
>>>>>>>>>>> >
>>>>>>>>>>> > Here
>>>>>>>>>>> > https://github.com/openpreserve/scape-xcorrsound/issues/17
>>>>>>>>>>> > this is a link to a tool which compares two sound files at the
>>>>>>>>>>> wave
>>>>>>>>>>> > level. You can also see the sound samples in the ticket.
>>>>>>>>>>> > The problem is, that currently this tool does not detect such
>>>>>>>>>>> slipping frames.
>>>>>>>>>>> >
>>>>>>>>>>> > I will also write a detailed article with examples, during the
>>>>>>>>>>> weekend.
>>>>>>>>>>> >
>>>>>>>>>>> >
>>>>>>>>>>> >
>>>>>>>>>>> >
>>>>>>>>>>> >
>>>>>>>>>>> >>
>>>>>>>>>>> >>
>>>>>>>>>>> >> 2015-04-04 12:53 GMT+02:00 Stanislav Sinyagin <
>>>>>>>>>>> ssinyagin at gmail.com>:
>>>>>>>>>>> >>>
>>>>>>>>>>> >>> Important is to send the media through two independent
>>>>>>>>>>> carriers - then you
>>>>>>>>>>> >>> can be sure that your clock is compared against a high
>>>>>>>>>>> quality one.
>>>>>>>>>>> >>>
>>>>>>>>>>> >>> On Apr 4, 2015 12:46 PM, "Regis M" <
>>>>>>>>>>> regis.freeswitch.org at tornad.net>
>>>>>>>>>>> >>> wrote:
>>>>>>>>>>> >>>>
>>>>>>>>>>> >>>> Hi,
>>>>>>>>>>> >>>>
>>>>>>>>>>> >>>> It's a very interresting test and conclusion.
>>>>>>>>>>> >>>>
>>>>>>>>>>> >>>> I will try to build a similar environnement on my
>>>>>>>>>>> freeswitch to check
>>>>>>>>>>> >>>> some system :)
>>>>>>>>>>> >>>>
>>>>>>>>>>> >>>> thanks
>>>>>>>>>>> >>>>
>>>>>>>>>>> >>>>
>>>>>>>>>>> >>>>
>>>>>>>>>>> >>>> 2015-04-04 2:16 GMT+02:00 Stanislav Sinyagin <
>>>>>>>>>>> ssinyagin at gmail.com>:
>>>>>>>>>>> >>>>>
>>>>>>>>>>> >>>>> hi,
>>>>>>>>>>> >>>>>
>>>>>>>>>>> >>>>> Here are some test results which might be interesting:
>>>>>>>>>>> >>>>>
>>>>>>>>>>> >>>>> I've set up a test FreeSWITCH server at digitalocean (they
>>>>>>>>>>> use KVM),
>>>>>>>>>>> >>>>> and originated test calls to some ITSP accounts. Each call
>>>>>>>>>>> played a
>>>>>>>>>>> >>>>> test sound file (voice samples from ITU:
>>>>>>>>>>> >>>>>
>>>>>>>>>>> http://www.itu.int/net/itu-t/sigdb/genaudio/AudioForm-g.aspx?val=1000050
>>>>>>>>>>> >>>>> ), and on the receiving end another FreeSWITCH server was
>>>>>>>>>>> recording
>>>>>>>>>>> >>>>> the received session. The receiving server was on a XEN
>>>>>>>>>>> VM. Both
>>>>>>>>>>> >>>>> servers talked G711 to their corresponding ITSP accounts.
>>>>>>>>>>> >>>>>
>>>>>>>>>>> >>>>> Then I compared the source audio and received audio in
>>>>>>>>>>> Audacity editor.
>>>>>>>>>>> >>>>>
>>>>>>>>>>> >>>>> The tests showed that the received voice wave shifts 20ms
>>>>>>>>>>> from the
>>>>>>>>>>> >>>>> original sound every few seconds, randomly back and
>>>>>>>>>>> forward. This
>>>>>>>>>>> >>>>> skewing was always present, regardless of ITSP and time of
>>>>>>>>>>> day.
>>>>>>>>>>> >>>>>
>>>>>>>>>>> >>>>> Then I moved the sending server to a XEN VM, and the waves
>>>>>>>>>>> appeared
>>>>>>>>>>> >>>>> almost perfectly synchronized (there was a 5ms skew in one
>>>>>>>>>>> test, and I
>>>>>>>>>>> >>>>> guess it's related to transcoding buffer, as the sound was
>>>>>>>>>>> obviously
>>>>>>>>>>> >>>>> transcoded).
>>>>>>>>>>> >>>>>
>>>>>>>>>>> >>>>> The effect was always visible with a 30-second sample, and
>>>>>>>>>>> I also made
>>>>>>>>>>> >>>>> additional tests with 2-minute samples.
>>>>>>>>>>> >>>>>
>>>>>>>>>>> >>>>> It would also be interesting to test this from a VmWare
>>>>>>>>>>> VM. If someone
>>>>>>>>>>> >>>>> wants to run such a test, feel free to contact me directly.
>>>>>>>>>>> >>>>>
>>>>>>>>>>> >>>>>
>>>>>>>>>>> >>>>> cheers,
>>>>>>>>>>> >>>>> stan
>>>>>>>>>>> >>>>>
>>>>>>>>>>> >>>>>
>>>>>>>>>>> >>>>>
>>>>>>>>>>> _________________________________________________________________________
>>>>>>>>>>> >>>>> Professional FreeSWITCH Consulting Services:
>>>>>>>>>>> >>>>> consulting at freeswitch.org
>>>>>>>>>>> >>>>> http://www.freeswitchsolutions.com
>>>>>>>>>>> >>>>>
>>>>>>>>>>> >>>>> Official FreeSWITCH Sites
>>>>>>>>>>> >>>>> http://www.freeswitch.org
>>>>>>>>>>> >>>>> http://confluence.freeswitch.org
>>>>>>>>>>> >>>>> http://www.cluecon.com
>>>>>>>>>>> >>>>>
>>>>>>>>>>> >>>>> FreeSWITCH-users mailing list
>>>>>>>>>>> >>>>> FreeSWITCH-users at lists.freeswitch.org
>>>>>>>>>>> >>>>>
>>>>>>>>>>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>>>>>>>>>> >>>>> UNSUBSCRIBE:
>>>>>>>>>>> http://lists.freeswitch.org/mailman/options/freeswitch-users
>>>>>>>>>>> >>>>> http://www.freeswitch.org
>>>>>>>>>>> >>>>
>>>>>>>>>>> >>>>
>>>>>>>>>>> >>>>
>>>>>>>>>>> >>>>
>>>>>>>>>>> _________________________________________________________________________
>>>>>>>>>>> >>>> Professional FreeSWITCH Consulting Services:
>>>>>>>>>>> >>>> consulting at freeswitch.org
>>>>>>>>>>> >>>> http://www.freeswitchsolutions.com
>>>>>>>>>>> >>>>
>>>>>>>>>>> >>>> Official FreeSWITCH Sites
>>>>>>>>>>> >>>> http://www.freeswitch.org
>>>>>>>>>>> >>>> http://confluence.freeswitch.org
>>>>>>>>>>> >>>> http://www.cluecon.com
>>>>>>>>>>> >>>>
>>>>>>>>>>> >>>> FreeSWITCH-users mailing list
>>>>>>>>>>> >>>> FreeSWITCH-users at lists.freeswitch.org
>>>>>>>>>>> >>>>
>>>>>>>>>>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>>>>>>>>>> >>>> UNSUBSCRIBE:
>>>>>>>>>>> http://lists.freeswitch.org/mailman/options/freeswitch-users
>>>>>>>>>>> >>>> http://www.freeswitch.org
>>>>>>>>>>> >>>
>>>>>>>>>>> >>>
>>>>>>>>>>> >>>
>>>>>>>>>>> _________________________________________________________________________
>>>>>>>>>>> >>> Professional FreeSWITCH Consulting Services:
>>>>>>>>>>> >>> consulting at freeswitch.org
>>>>>>>>>>> >>> http://www.freeswitchsolutions.com
>>>>>>>>>>> >>>
>>>>>>>>>>> >>> Official FreeSWITCH Sites
>>>>>>>>>>> >>> http://www.freeswitch.org
>>>>>>>>>>> >>> http://confluence.freeswitch.org
>>>>>>>>>>> >>> http://www.cluecon.com
>>>>>>>>>>> >>>
>>>>>>>>>>> >>> FreeSWITCH-users mailing list
>>>>>>>>>>> >>> FreeSWITCH-users at lists.freeswitch.org
>>>>>>>>>>> >>>
>>>>>>>>>>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>>>>>>>>>> >>> UNSUBSCRIBE:
>>>>>>>>>>> http://lists.freeswitch.org/mailman/options/freeswitch-users
>>>>>>>>>>> >>> http://www.freeswitch.org
>>>>>>>>>>> >>
>>>>>>>>>>> >>
>>>>>>>>>>> >>
>>>>>>>>>>> >>
>>>>>>>>>>> _________________________________________________________________________
>>>>>>>>>>> >> Professional FreeSWITCH Consulting Services:
>>>>>>>>>>> >> consulting at freeswitch.org
>>>>>>>>>>> >> http://www.freeswitchsolutions.com
>>>>>>>>>>> >>
>>>>>>>>>>> >> Official FreeSWITCH Sites
>>>>>>>>>>> >> http://www.freeswitch.org
>>>>>>>>>>> >> http://confluence.freeswitch.org
>>>>>>>>>>> >> http://www.cluecon.com
>>>>>>>>>>> >>
>>>>>>>>>>> >> FreeSWITCH-users mailing list
>>>>>>>>>>> >> FreeSWITCH-users at lists.freeswitch.org
>>>>>>>>>>> >> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>>>>>>>>>> >> UNSUBSCRIBE:
>>>>>>>>>>> http://lists.freeswitch.org/mailman/options/freeswitch-users
>>>>>>>>>>> >> http://www.freeswitch.org
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> _________________________________________________________________________
>>>>>>>>>>> Professional FreeSWITCH Consulting Services:
>>>>>>>>>>> consulting at freeswitch.org
>>>>>>>>>>> http://www.freeswitchsolutions.com
>>>>>>>>>>>
>>>>>>>>>>> Official FreeSWITCH Sites
>>>>>>>>>>> http://www.freeswitch.org
>>>>>>>>>>> http://confluence.freeswitch.org
>>>>>>>>>>> http://www.cluecon.com
>>>>>>>>>>>
>>>>>>>>>>> FreeSWITCH-users mailing list
>>>>>>>>>>> FreeSWITCH-users at lists.freeswitch.org
>>>>>>>>>>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>>>>>>>>>> UNSUBSCRIBE:
>>>>>>>>>>> http://lists.freeswitch.org/mailman/options/freeswitch-users
>>>>>>>>>>> http://www.freeswitch.org
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> _________________________________________________________________________
>>>>>>>>>> Professional FreeSWITCH Consulting Services:
>>>>>>>>>> consulting at freeswitch.org
>>>>>>>>>> http://www.freeswitchsolutions.com
>>>>>>>>>>
>>>>>>>>>> Official FreeSWITCH Sites
>>>>>>>>>> http://www.freeswitch.org
>>>>>>>>>> http://confluence.freeswitch.org
>>>>>>>>>> http://www.cluecon.com
>>>>>>>>>>
>>>>>>>>>> FreeSWITCH-users mailing list
>>>>>>>>>> FreeSWITCH-users at lists.freeswitch.org
>>>>>>>>>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>>>>>>>>> UNSUBSCRIBE:
>>>>>>>>>> http://lists.freeswitch.org/mailman/options/freeswitch-users
>>>>>>>>>> http://www.freeswitch.org
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> _________________________________________________________________________
>>>>>>>>> Professional FreeSWITCH Consulting Services:
>>>>>>>>> consulting at freeswitch.org
>>>>>>>>> http://www.freeswitchsolutions.com
>>>>>>>>>
>>>>>>>>> Official FreeSWITCH Sites
>>>>>>>>> http://www.freeswitch.org
>>>>>>>>> http://confluence.freeswitch.org
>>>>>>>>> http://www.cluecon.com
>>>>>>>>>
>>>>>>>>> FreeSWITCH-users mailing list
>>>>>>>>> FreeSWITCH-users at lists.freeswitch.org
>>>>>>>>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>>>>>>>> UNSUBSCRIBE:
>>>>>>>>> http://lists.freeswitch.org/mailman/options/freeswitch-users
>>>>>>>>> http://www.freeswitch.org
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> _________________________________________________________________________
>>>>>>>> Professional FreeSWITCH Consulting Services:
>>>>>>>> consulting at freeswitch.org
>>>>>>>> http://www.freeswitchsolutions.com
>>>>>>>>
>>>>>>>> Official FreeSWITCH Sites
>>>>>>>> http://www.freeswitch.org
>>>>>>>> http://confluence.freeswitch.org
>>>>>>>> http://www.cluecon.com
>>>>>>>>
>>>>>>>> FreeSWITCH-users mailing list
>>>>>>>> FreeSWITCH-users at lists.freeswitch.org
>>>>>>>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>>>>>>> UNSUBSCRIBE:
>>>>>>>> http://lists.freeswitch.org/mailman/options/freeswitch-users
>>>>>>>> http://www.freeswitch.org
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> _________________________________________________________________________
>>>>>>> Professional FreeSWITCH Consulting Services:
>>>>>>> consulting at freeswitch.org
>>>>>>> http://www.freeswitchsolutions.com
>>>>>>>
>>>>>>> Official FreeSWITCH Sites
>>>>>>> http://www.freeswitch.org
>>>>>>> http://confluence.freeswitch.org
>>>>>>> http://www.cluecon.com
>>>>>>>
>>>>>>> FreeSWITCH-users mailing list
>>>>>>> FreeSWITCH-users at lists.freeswitch.org
>>>>>>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>>>>>> UNSUBSCRIBE:
>>>>>>> http://lists.freeswitch.org/mailman/options/freeswitch-users
>>>>>>> http://www.freeswitch.org
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> _________________________________________________________________________
>>>>>> Professional FreeSWITCH Consulting Services:
>>>>>> consulting at freeswitch.org
>>>>>> http://www.freeswitchsolutions.com
>>>>>>
>>>>>> Official FreeSWITCH Sites
>>>>>> http://www.freeswitch.org
>>>>>> http://confluence.freeswitch.org
>>>>>> http://www.cluecon.com
>>>>>>
>>>>>> FreeSWITCH-users mailing list
>>>>>> FreeSWITCH-users at lists.freeswitch.org
>>>>>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>>>>> UNSUBSCRIBE:
>>>>>> http://lists.freeswitch.org/mailman/options/freeswitch-users
>>>>>> http://www.freeswitch.org
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>> _________________________________________________________________________
>>>>> Professional FreeSWITCH Consulting Services:
>>>>> consulting at freeswitch.org
>>>>> http://www.freeswitchsolutions.com
>>>>>
>>>>> Official FreeSWITCH Sites
>>>>> http://www.freeswitch.org
>>>>> http://confluence.freeswitch.org
>>>>> http://www.cluecon.com
>>>>>
>>>>> FreeSWITCH-users mailing list
>>>>> FreeSWITCH-users at lists.freeswitch.org
>>>>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>>>> UNSUBSCRIBE:
>>>>> http://lists.freeswitch.org/mailman/options/freeswitch-users
>>>>> http://www.freeswitch.org
>>>>>
>>>>
>>>>
>>>>
>>>> _________________________________________________________________________
>>>> Professional FreeSWITCH Consulting Services:
>>>> consulting at freeswitch.org
>>>> http://www.freeswitchsolutions.com
>>>>
>>>> Official FreeSWITCH Sites
>>>> http://www.freeswitch.org
>>>> http://confluence.freeswitch.org
>>>> http://www.cluecon.com
>>>>
>>>> FreeSWITCH-users mailing list
>>>> FreeSWITCH-users at lists.freeswitch.org
>>>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>>> UNSUBSCRIBE:
>>>> http://lists.freeswitch.org/mailman/options/freeswitch-users
>>>> http://www.freeswitch.org
>>>>
>>>
>>>
>>> _________________________________________________________________________
>>> Professional FreeSWITCH Consulting Services:
>>> consulting at freeswitch.org
>>> http://www.freeswitchsolutions.com
>>>
>>> Official FreeSWITCH Sites
>>> http://www.freeswitch.org
>>> http://confluence.freeswitch.org
>>> http://www.cluecon.com
>>>
>>> FreeSWITCH-users mailing list
>>> FreeSWITCH-users at lists.freeswitch.org
>>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
>>> http://www.freeswitch.org
>>>
>>
>>
>> _________________________________________________________________________
>> Professional FreeSWITCH Consulting Services:
>> consulting at freeswitch.org
>> http://www.freeswitchsolutions.com
>>
>> Official FreeSWITCH Sites
>> http://www.freeswitch.org
>> http://confluence.freeswitch.org
>> http://www.cluecon.com
>>
>> FreeSWITCH-users mailing list
>> FreeSWITCH-users at lists.freeswitch.org
>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
>> http://www.freeswitch.org
>>
>
>
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