[asterisk-users] TE121 - Idle system load at ~0.3 - Bad DAHDI 2.2.0.2 behaviour ?!

[Ex Vito]

 Shaun,

 Thanks for your feedback. See my inline comments.


On Fri, Nov 13, 2009 at 7:18 PM, Shaun Ruffell <sruffell at digium.com> wrote:
>
> It appears there may be a regression in dahdi-linux 2.2.0 with regards to
> the wcte12xp driver and the VPMADT032 module (as discussed
> https://issues.asterisk.org/view.php?id=15724).  Would you be willing to try
> at least revision 7584 of
> http://svn.asterisk.org/svn/dahdi/linux/branches/2.2 and report your results
> on that issue?
>

 We will, either on 15724 or on 15798, both, I'd say, closely related
 to what we're experiencing.

 First, however, we will test 2.1.0.4 for at least 10 days to
 effectively confirm are experiencing the regression you refer. We
 defined 10 stable days because we've been experiencing 1 - 3
 failures per week with 2.2.0.2.

 So, we will move to 2.1.0.4 later today and, if there are no incidents,
 we will move to SVN revision 7584 or later on Nov 27th.


>
> The idle load you're seeing can be a little misleading, but essentially,
> once you load the drivers for both the wctdm24xxp and wcte12xp, there is a
> fixed cost associated with continuously moving the TDM data to/from the
> card.  The load imposed by the drivers would only go up after this point if
> a) software echocan is enabled, or b) you're conferencing many calls in the
> kernel.  Otherwise....it's fixed.
>

 I agree the load can be misleading however, consider:

 - The system is really idle - zero calls, zero activity, no other software.
 - 0.3 to 0.4 load on a modern CPU is a lot of processing, is there
   that much data to move around ?! :)

 We tested some variations and here is what we found:
 (recall, AEX410 with no VPM is physically installed)

 DAHDI 2.2.0.2
 - Removed TE121 - Idle load is 0
 - TE121 without VPM - Idle load is 0.3 - 0.4
 - TE121 with VPM - Idle load is 0.3 - 0.4

 DAHDI 2.1.0.4
 - TE121 without VPM - Idle load is 0.01 - 0.02
 - TE121 with VPM - Idle load is 0.01 - 0.05

 DAHDI 2.2.0.1
 - TE121 with VPM - Idle load is 0.26 - 0.32

 DAHDI 2.2.0
 - TE121 with VPM - Idle load is 0.31 - 0.36

 DAHDI SVN-branch-2.2-r7584
 - TE121 with VPM - Idle load is 0.69 - 0.82

 Under all cases, we stopped asterisk, unloaded DAHDI,
 rebuilt DAHDI (+Asterisk if needed), loaded DAHDI, started
 Asterisk, waited 120s, tested one inbound call + one outbound
 call.

 In short:

 - DAHDI 2.1, Idle load is 0
 - DAHDI 2.2, Idle load is 0.3 - 0.4
 - DAHDI 2.2. SVN, Idle load is roughly twice as in 2.2 releases

 So, while your explanation regarding system load makes sense,
 I find it odd that 2.2, which apparently is not working ok for us
 in this case, is showing such behaviour when 2.1 does not and
 neither Zaptel 1.2/1.4 used many other systems I've installed.

 What would you say the explanation for these observations is ?

 Would you say that there is a correlation between the load and
 the suspected not so good behaviour we're getting from DAHDI
 2.2.0.2 on our case ?

 Or is it just a coincidence ?


 Cheers,
--
 exvito