Yes, it might be a typo. IIRC it should be usec for time_test. The small sample of timer_test you provided seems ok to me, +/- 40 usec is probably good enough.

I think you're good to go :)

/Peter

2013/8/29 Jayanth Acharya <jayachar88@gmail.com>

On Thu, Aug 29, 2013 at 1:28 PM, Peter Olsson <peter@olssononline.se> wrote:

I believe that timerfd is used automatically in the core if it detects a system supporting it. However, I don't know how to really be sure.. :) One thing though, if you just startup FS, if it doesn't try to do clock calibration during startup, I think it is using timerfd stuff, so that might be a way to "know"...

Also, when running FS, you can try timer_test command (inside FS console) and check out the results in there.

Thanks Peter.

freeswitch@dabbian1> timer_test 10 3
2013-08-29 13:56:24.703028 [CONSOLE] mod_commands.c:827 Timer Test: 1 sleep 10 10019
2013-08-29 13:56:24.712967 [CONSOLE] mod_commands.c:827 Timer Test: 2 sleep 10 9930
2013-08-29 13:56:24.722996 [CONSOLE] mod_commands.c:827 Timer Test: 3 sleep 10 10040

Avg: 9.996ms Total Time: 29.989ms

However,  for the "time_test" command in Mod_commands Wiki page -- I see that it assumes units as "microseconds" (not milliseconds, which is usually what we mean by "ms").. or is it a typo ??

... bad timer jitter is. It runs the test count times (default 10) and tries to sleep for mss microseconds. It returns the actual timer duration along with an average.

 

Anyhow, not sure how to interpret if the output of timer_test indicates a healthy resolution or not.

/Peter

2013/8/29 Jayanth Acharya <jayachar88@gmail.com>

Thanks Jeff. Reading the mod_timerfd wiki page, I see that there are 2 approaches to using timerfd,

1. Using the loadable module i.e. mod_timerfd (requiring me to build this module and then ensure it is loaded)

2. Using the support of timerfd now available in FS core itself (requiring me to just enable it in the switch.conf file)

By default neither of those 2 seem to be true. I am on what as the Git HEAD last week - 22nd Aug 2013, so pretty recent source. However, it when I adopted the 2nd approach, i.e. enable timerfd use in FS core, by enabling the config in switch.conf, it didn't have the desired effect. Perhaps indicating that my problems might not be limited to just the timer resolution !!

Using the method described here:
http://www.advenage.com/topics/linux-timer-interrupt-frequency.php

I tested and found that on my FS machine, the timer resolution available is already pretty good -- in the ~3KHz range, so shouldn't be an issue, if FS core is indeed correctly using timerfd.

---
kernel timer interrupt frequency is approx. 3401 Hz
jayachar@dabbian1:~$ ./timer_resolution_test
kernel timer interrupt frequency is approx. 3401 Hz
jayachar@dabbian1:~$ ./timer_resolution_test
kernel timer interrupt frequency is approx. 3448 Hz
jayachar@dabbian1:~$ ./timer_resolution_test
kernel timer interrupt frequency is approx. 3021 Hz
jayachar@dabbian1:~$ ./timer_resolution_test
kernel timer interrupt frequency is approx. 3067 Hz
---

I have already check that my kernel has the TIMERFD option enabled in the build, which explains (perhaps) the ~3KHz resolution I see.

So the question now is, is FS really using the timerfd logic in it's core properly, or do I need to try the mod_timerfd method as well !! (That's a rhetorical question... I will go ahead and try anyway, disabling the FS core option to use timerfd, as per the Wiki).

On Thu, Aug 29, 2013 at 11:21 AM, Jeff Leung <jleung@v10networks.ca> wrote:

If I can recall correctly, timerfd will be used automatically regardless in recent versions of FreeSWITCH if it’s available.

 

From: freeswitch-users-bounces@lists.freeswitch.org [mailto:freeswitch-users-bounces@lists.freeswitch.org] On Behalf Of Jayanth Acharya
Sent: Wednesday, August 28, 2013 9:35 PM
To: FreeSWITCH Users Help
Subject: [Freeswitch-users] CONFIG_HZ=1000 vs mod_timerfd -- preferred approach

 

Assuming that one has full control over the kernel configuration and FS build / config options, is there a preferred mechanism between the 2 for letting FS have access to high resolution timers, i.e.

• CONFIG_HZ=1000
• mod_timerfd

This was one step I missed in my FS setup, and I think it might explain the extremely choppy, broken, garbled announcement I hear when I call into my gsmopen EP via phone.

J

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