[Jack-Devel] AVB

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DateSun, 22 Sep 2013 22:03:27 +0200
From Jörn Nettingsmeier <[hidden] at stackingdwarves dot net>
To"Mann, Eric" <[hidden] at intel dot com>
CcJACK <[hidden] at lists dot jackaudio dot org>
In-Reply-ToMann, Eric Re: [Jack-Devel] Very low latency audio 
On 09/20/2013 04:42 PM, Mann, Eric wrote:
> Maybe I’m mis-understanding the device, but you can generally do < 64
> byte DMA transfers over PCIe … they are called partials. They aren’t
> particularly efficient from a bus and memory utilization perspective ..
>   you start to see the inefficiency as you approach back-to-back
> transfers -> 1 usec (at least on current CPUs … some 6+ yr old laptop
> its probably in the 10-20 usec area … close to a 48KHz sample rate … ).
>
> The current state of the art for low-latency **anything** is to avoid
> interrupts (as an interrupt itself is ~1-2 usec of processing latency) –
> either in-kernel (e.g. 3.11’s low-latency sockets) or in user space.
>
> Eric Mann / Intel Networking Division

totally off-topic, but good to see AVB people lurking on (and 
contributing to) jack-devel.

lurking on the AVB list myself, after adi+christoph got me interested at 
LAC 2013.

i wonder if we could dedicate some spacetime at LAC 2014 to AVB related 
issues again...


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