[asterisk-users] Recommendations for kernel config

[Matthew J. Roth]

Alan Lord wrote:
> I'm building a test asterisk server and building the latest kernel I got 
> to wonder if there are any specific recommendations about schedulers and 
> so forth for optimum performance.
>
> There are a few areas that raise questions in my mind and I wonder if 
> anyone has any opinions/comments on which settings are most suitable for 
> use with asterisk:
>
> SLAB Allocator (SLAB or SLUB?)
> Tickless System (?)
> Preemption model (?)
> IO Scheduler (Anticipatory, Deadline or CFQ?)
> Flat or Sparse Memory (?)
> Timer Frequency (100Hz .. 1000hz)
>   
Alan,

Good post!  I've wondered about the preemption model and I/O scheduler 
myself, so I'll be keeping an eye on this thread.  As the Linux kernel 
evolves to allow configuration as a fully deterministic real-time OS, it 
will be interesting to see what settings provide the optimal environment 
for Asterisk.

As for my contribution to the thread, I have a few tips for configuring 
the kernel if you plan on using ztdummy for timing:

  1. The kernel version must be at least 2.6.13
  2. The kernel must be configured with a timer frequency of 1000 HZ
  3. The kernel must be configured to provide RTC interrupts
  4. The kernel must be configured with enhanced real time clock support

Remember to use zttest to verify the accuracy of your timing source.  
The goal is to obtain at least 99.98% output from zttest

Regards,

Matthew Roth
InterMedia Marketing Solutions
Software Engineer and Systems Developer