Hi thank you for your response. Here is my code used for testing the latency http://pastebin.com/mwHrRDeK. It is based on and built as freeswitch-git/libs/freetdm/src/testapp.c For the measurement I used a104d card with interconnected spans 1&2. App loads binary file "sample_binin" which was previously created by dumping the E1 channel when there was active call. This dump is used as a source of voice. App initiates a call on span1. App handles it as incoming call on span2. After call is established, measurement loop is entered,measurement is in single thread world, handling the spans 1 & 2 in "serial". App feeds prebuffered voice to outgoing call on span1 and in paralell makes a dump of written data to binary file "owbinout". At the same time, data read from the span1 are dumped to binary file "orbinout". Then span2 is handled, data read from the active channel are just written back, here the loopback is created. In paralell data are dumped to file "awbinout" So then results are being calculated by comparing the content of : owbinout against awbinout = one way delay owbinout against orbinout = roundtrip delay Personally I use Audacity to import the binary voice, decode it and pair in stereotracks so I can measure the delay. With this approach I got the results posted earlier. With best regards Juraj Fabo

---------- Forwarded message ---------- From: Moises Silva <moises.silva@gmail.com> To: freeswitch-dev@lists.freeswitch.org Date: Mon, 17 Oct 2011 12:22:58 -0400 Subject: Re: [Freeswitch-dev] MTU setting and application buffer size On Tue, Oct 4, 2011 at 8:56 AM, Juraj Fabo <juraj.fabo@gmail.com> wrote:

...

...

Please, have a look at the results with various parameters used: mtu:80 txqueue_size=1 rxqueue_size=1 one-direction delay=60ms round-trip delay=120ms mtu:80 txqueue_size=2 rxqueue_size=2 one-direction delay=80ms round-trip delay=160ms mtu:80 txqueue_size=10 rxqueue_size=10 one-direction delay=240ms round-trip delay=480ms mtu:40 txqueue_size=1 rxqueue_size=1 one-direction delay=40ms round-trip delay=80ms mtu:40 txqueue_size=2 rxqueue_size=2 one-direction delay=60ms round-trip delay=120ms mtu:40 txqueue_size=5 rxqueue_size=5 one-direction delay=120ms round-trip delay=240ms mtu:16 txqueue_size=1 rxqueue_size=1 one-direction delay=30ms round-trip delay=60ms mtu:8 txqueue_size=1 rxqueue_size=1 one-direction delay=25ms round-trip delay=50ms mtu:8 txqueue_size=10 rxqueue_size=10 one-direction delay=205ms round-trip delay=410ms

Updated test result with the codec_ms=10 is following: mtu:16 txqueue_size=1 rxqueue_size=10 one-direction delay=20ms round-trip delay=50ms mtu:80 txqueue_size=1 rxqueue_size=10 one-direction delay=56ms round-trip delay=110ms

However, this is still not 10ms with the default MTU:80 and codec_ms:10 :(

Anyway, is it a good idea to use so assymetric tx/rx queue sizes?

In general I don't think is a good idea because 99% of the user population is using default symmetric queues, moving to obscure/rarely-tested configurations increases your likelihood of facing problems. Having said that, I don't see why it should not work :-)

Can you share the code you're using to measure latency? may be setup a git repo in github with your code?

*Moises Silva **Software Engineer, Development Manager***

msilva@sangoma.com

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