[LAU] rtirq failure

Len Ovens len at ovenwerks.net
Sun Aug 9 00:25:48 UTC 2015

On Sat, 8 Aug 2015, Ralf Mardorf wrote:

> On Sat, 8 Aug 2015 20:46:17 +0100, Rui Nuno Capela wrote:

>> so you're left with the RTIRQ_NAME_LIST="snd_hdsp"... workaround for
>> sure.
> Rui, thank you for the explanation.
> It's not a workaround for me, I anyway would add snd_hdsp to ensure
> that it gets a higher priority, than the Envy24 cards. I just worried
> about it, because I didn't know, if it could become an issue for other
> set-ups, used by others or maybe used by me in the future.
> Without a script that works around this issue, for this card and perhaps
> other cards, a default config to provide usable priorities for all
> snd devices isn't ensured. That's a pity.

As someone who has tested more than one system, I do not think there is 
any such thing as a generic RTIRQ_NAME_LIST since early PCI days. Both FW 
and USB require hand editing the config file anyway for best use. The 
default generally works ok as it just prioritizes pciaudio, USB and FW 
"stuff". But it just works "ok". Getting good lowlatency out of it 
requires hand editting.

For example, almost all USB setups I have played with have at least one 
USB port that:
 	- shares an irq with 3 or 4 other things
 	- is a hub with internal USB bits (mics. wifi, camera, mouse, etc)
This means that the USB audio IF must be plugged into a "Clean" USB port 
and so things like RTIRQ_NAME_LIST="usb3 snd usb" will work where "usb 
snd" will not because usb2 may have mouse traffic on it that ends up 
prioritized ahead of usb3 with the audio.

The thing is that this is system stuff not user. Making a GUI to edit 
things inteligently and securely has not been done that I know of, but may 
be a good solution.

Len Ovens

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