[asterisk-users] Prompts playback changing tempo w/ SMP kernel

[Leo Ann Boon]

RR wrote:
> Hi Leo,
>
> Sorry mate, I thought I had done some research but I only found one
> reference to it somewhere and it stated that if you have more than one
> VM running inside VMWare server v1.0, then there are timing issues
> where the clock seems to vary randomly. I figured that didn't apply to
> me since I had the latest version and I was only running 1 VM. I
> should've used a better search criteria maybe :( The only way I
> discovered it was the VM was by actually getting one of my HT machines
> and installing (*) on it with SMP and it works fine natively. Just
> VMWare server seems to have timing issues. Again, sorry for that.
Most virtualization platforms don't guarantee accurate timing. It's a 
fundamental implementation issue. For example, if your host OS is 
capable of 1000Hz. You won't expect the client OS to be able to do 
1000Hz due to the overheads. Best case might be 999.9Hz, worse case 
could be anything below that. IIRC, Xen VM used to do only 100Hz.
>
> BTW, do u happen to know if it's even worth my while to use SMP? I've
> read conflicting reports. I guess it would depend on (*) being
> multi-threaded or rather chan_sip being multi-threaded? is that the
> case?
Asterisk is multi-threaded so SMP (either multi-way or multi-core) would 
definitely help. But, HT would not. HT is still essentially still 1 CPU. 
The CPU appears as 2 CPU by taking advantage of wait times to 
multi-task. Good for normal usage like word processing, but bad when 
running CPU-intensive tasks like codec transcoding.

Leo.