[Freeswitch-users] KVM vs. XEN virtualization
Anthony Minessale
anthony.minessale at gmail.com
Mon Apr 6 19:30:16 MSD 2015
Depending on the host and guest OS the timing will be a product of several
thing.
If some of the features FS tries to detect are emulated, it can be a
problem.
The primary thing FS looks for is a kernel with timerfd support.
This should be the most accurate. If the guest OS supports timerfd but its
using emulated hardware, it might not work as well as it should.
So on something like openvz, you might have support for timerfd in your
debian 7/8 instance but the host kernel has no support at all.
So in theory kvm would be preferred since it actually boots the guest
kernel and you have a chance for it to hit the real timer hardware.
If no timerfd is present, it reverts to the single thread ms precision
thread with conditional broadcast for timing.
You can also manually configure a combo of one timerfd timer and shared
broadcast.
This param in switch.conf.xml helps to tune a few behavior you might want
to compare results on.
enable-softtimer-timerfd
true|fd-per-timer --- Use one fd for each timer instance (default)
false --- Don't use timerfd at all
broadcast --- Use one timerfd and share it with conditional
broadcasts
This is one reason we do not support virtualization as its too variable to
provide definitive policies to make things work every time.
On Mon, Apr 6, 2015 at 10:17 AM, Stanislav Sinyagin <ssinyagin at gmail.com>
wrote:
> I didn't yet have time to learn this utility - how do we interpret the
> results?
> On Apr 6, 2015 4:39 PM, "Errol Samuels" <ewsamuels at gmail.com> wrote:
>
>> Ok Sergey,
>>
>> Here it goes:
>>
>> Test 1
>> ====
>> *VM: *Digital Ocean KVM at AMS3 / 2 Cores / 2GB Ram / 40GB SSD
>> *OS:* Debian Wheezy 7.8 64 bit / Linux 3.2.0-4-amd64 x86_64
>>
>> policy: fifo: loadavg: 6.22 1.53 0.58 1/164 31050 : 195 Max:
>> 42869
>> T:12 (31021) P:80 I:125 C: 238830 Min: 2 Act: 18 Avg: 196 Max:
>> 42846
>> T: 0 (31009) P:80 I:125 C: 239000 Min: 2 Act: 12 Avg: 190 Max:
>> 42845
>> T: 1 (31010) P:80 I:125 C: 239002 Min: 2 Act: 18 Avg: 196 Max:
>> 42866
>> T: 2 (31011) P:80 I:125 C: 239004 Min: 3 Act: 10 Avg: 191 Max:
>> 42890
>> T: 3 (31012) P:80 I:125 C: 239004 Min: 3 Act: 8 Avg: 197 Max:
>> 42876
>> T: 4 (31013) P:80 I:125 C: 239005 Min: 2 Act: 27 Avg: 194 Max:
>> 42846
>> T: 5 (31014) P:80 I:125 C: 239008 Min: 2 Act: 26 Avg: 196 Max:
>> 42872
>> T: 6 (31015) P:80 I:125 C: 239013 Min: 2 Act: 12 Avg: 196 Max:
>> 42843
>> T: 7 (31016) P:80 I:125 C: 239013 Min: 2 Act: 19 Avg: 194 Max:
>> 42848
>> T: 8 (31017) P:80 I:125 C: 239013 Min: 2 Act: 14 Avg: 190 Max:
>> 42856
>> T: 9 (31018) P:80 I:125 C: 239014 Min: 2 Act: 14 Avg: 197 Max:
>> 42865
>> T:10 (31019) P:80 I:125 C: 239016 Min: 2 Act: 9 Avg: 197 Max:
>> 42868
>>
>>
>> Test 2
>> ====
>> *VM: *Linode (Xen) London / 8 Cores (E5-2670 0 @ 2.60GHz) / 4GB Ram
>> *OS:* Ubuntu 12.04.4 LTS / Linux 3.18.5-x86_64-linode52 x86_64
>>
>> policy: fifo: loadavg: 6.50 1.56 0.55 15/246 30752 97 Max:
>> 1030
>> T:16 (30726) P:80 I:125 C: 239853 Min: 5 Act: 77 Avg: 97 Max:
>> 1066
>> T: 0 (30710) P:80 I:125 C: 239946 Min: 5 Act: 63 Avg: 98 Max:
>> 1245
>> T: 1 (30711) P:80 I:125 C: 239946 Min: 5 Act: 67 Avg: 98 Max:
>> 1091
>> T: 2 (30712) P:80 I:125 C: 239945 Min: 5 Act: 119 Avg: 97 Max:
>> 1351
>> T: 3 (30713) P:80 I:125 C: 239945 Min: 5 Act: 99 Avg: 98
>> Max: 932
>> T: 4 (30714) P:80 I:125 C: 239945 Min: 5 Act: 35 Avg: 98 Max:
>> 1413
>> T: 5 (30715) P:80 I:125 C: 239945 Min: 5 Act: 35 Avg: 98 Max:
>> 1407
>> T: 6 (30716) P:80 I:125 C: 239944 Min: 5 Act: 110 Avg: 97 Max:
>> 1173
>> T: 7 (30717) P:80 I:125 C: 239947 Min: 5 Act: 85 Avg: 99 Max:
>> 1144
>> T: 8 (30718) P:80 I:125 C: 239948 Min: 4 Act: 69 Avg: 99
>> Max: 916
>> T: 9 (30719) P:80 I:125 C: 239947 Min: 4 Act: 40 Avg: 97
>> Max: 916
>> T:10 (30720) P:80 I:125 C: 239948 Min: 5 Act: 61 Avg: 97 Max:
>> 1024
>> T:11 (30721) P:80 I:125 C: 239946 Min: 6 Act: 84 Avg: 98 Max:
>> 2082
>> T:12 (30722) P:80 I:125 C: 239947 Min: 4 Act: 40 Avg: 98 Max:
>> 2142
>> T:13 (30723) P:80 I:125 C: 239946 Min: 5 Act: 49 Avg: 98 Max:
>> 1986
>> T:14 (30724) P:80 I:125 C: 239946 Min: 4 Act: 113 Avg: 99 Max:
>> 2061
>>
>> This is with system defaults.
>>
>> regards,
>>
>> Errol
>>
>>
>>
>>
>> On Mon, Apr 6, 2015 at 1:27 PM, Sergey Safarov <s.safarov at gmail.com>
>> wrote:
>>
>>> 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
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>>>>> >>>>> 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
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>>>>> >>>
>>>>> >>>
>>>>> >>>
>>>>> _________________________________________________________________________
>>>>> >>> 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
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>>>>> >>
>>>>> >>
>>>>> >>
>>>>> >>
>>>>> _________________________________________________________________________
>>>>> >> 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
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>>>>> >> UNSUBSCRIBE:
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>>>>>
>>>>>
>>>>> _________________________________________________________________________
>>>>> 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
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>>>>>
>>>>
>>>>
>>>>
>>>> _________________________________________________________________________
>>>> 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
>>>>
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>>>>
>>>
>>>
>>> _________________________________________________________________________
>>> Professional FreeSWITCH Consulting Services:
>>> consulting at freeswitch.org
>>> http://www.freeswitchsolutions.com
>>>
>>> Official FreeSWITCH Sites
>>> http://www.freeswitch.org
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>>>
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>>>
>>
>>
>> _________________________________________________________________________
>> 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
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>>
>
> _________________________________________________________________________
> 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
>
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>
--
Anthony Minessale II ♬ @anthmfs ♬ @FreeSWITCH ♬
☞ http://freeswitch.org/ ☞ http://cluecon.com/ ☞
http://twitter.com/FreeSWITCH
☞ irc.freenode.net #freeswitch ☞ *http://freeswitch.org/g+
<http://freeswitch.org/g+>*
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https://www.youtube.com/watch?v=9XXgW34t40s
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