[Freeswitch-users] CONFIG_HZ=1000 vs mod_timerfd -- preferred approach

[Peter Olsson]

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 at gmail.com>

> On Thu, Aug 29, 2013 at 1:28 PM, Peter Olsson <peter at 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 at 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 at 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 at dabbian1:~$ ./timer_resolution_test
>>> kernel timer interrupt frequency is approx. 3401 Hz
>>> jayachar at dabbian1:~$ ./timer_resolution_test
>>> kernel timer interrupt frequency is approx. 3448 Hz
>>> jayachar at dabbian1:~$ ./timer_resolution_test
>>> kernel timer interrupt frequency is approx. 3021 Hz
>>> jayachar at 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 at 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 at lists.freeswitch.org [mailto:
>>>> freeswitch-users-bounces at 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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>>
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>
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>
> 
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