Re: [Xen-devel] [PATCH v5] sndif: add ABI for Para-virtual sound

[Vitaly Chernooky <vitalii.chernookyi@xxxxxxxxxxxxxxx>]

Ian,

That numbers correspond only particular single usecase - mp3 playback and are close to common for that usecase.

For live audio usecases there will be numbers close for common in that usecases.

Olexandr,

Could you measure and provide us numbers for some live audio usecase?

With best regards,

Vitaly Chernooky

On Thu, Jan 22, 2015 at 6:11 PM, Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx> wrote:

Oleksandr Dmytryshyn writes ("Re: [Xen-devel] [PATCH v5] sndif: add ABI for Para-virtual sound"):
> On Thu, Jan 22, 2015 at 5:56 PM, Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx> wrote:
> > Oleksandr Dmytryshyn writes ("Re: [Xen-devel] [PATCH v5] sndif: add ABI for Para-virtual sound"):
> >> In my case this is about 3 packets per second with size about 16 KBytes.
> >
> > That would put a floor on the latency of about 300ms. I suspect
> > that's quite undesirable.
>
> This latency doesn't affect us because frontend and backend driver have
> an separate thread for each virtualized stream. And when frontend driver
> waits answer from the backend it just sleeps (in case Linux kernel it waits
> for the completion).

Your seem to be answering a different question to the one I intended
to ask.

What I mean is this:

Many people think it is important to reduce the latency of sound input
and output. So, they want to reduce (a) the time between a piece of
software deciding to make a sound and (b) the time when that sound
starts to appear. And the same for input. This is important for
games, video conversations, and so on.

When sound output is occurring continuously, any piece of new sound
output needs to wait for the next packet to be sent.

If you are sending only 3 packets per second then the latency might be
as much as 1/3 second which I think is probably too much.

Ian.

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel

--

Vitaly Chernooky |ÂSenior Developer - Product Engineering and Development

GlobalLogic

P +380.44.4929695 ext.1136 M +380.98.7920568 S cvv_2k

www.globallogic.com

http://www.globallogic.com/email_disclaimer.txt

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel