[asterisk-users] Problems with the voice quality under load

[A J Stiles]

On Monday 02 Mar 2015, Mordechay Kaganer wrote:
> When a particular server gets about 500 concurrent calls, the sound quality
> begins to degrade, the sound plays slowly and with clicks. As far as i
> understand, it's because asterisk is unable to send the voice stream in
> time i.e. the server is overloaded.
> 
> What i don't understand is, at the time that the server appears to be
> overloaded and the audio quality is bad, actual server's load is no more
> than 30-40% (60-70% idle CPU on average). IMHO, this indicates that for
> some reason the server is unable to use it's CPU capacity efficiently. May
> be because of some kind of thread contention inside asterisk?
> 
> Do you have any advice for me (other than purchasing more servers ;-) ?

Perhaps it's not CPU that is blocking things, but I/O?  It should be visually 
and audibly obvious if this is the case -- the disk activity lights will be 
illuminated, and the HDDs will be making noises.

If you can spare the RAM, consider setting up a tmpfs to hold your IVR prompts 
in memory.

-- 
AJS

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