[LAU] linux-rt & presonus 1818VSL

Harry van Haaren harryhaaren at gmail.com
Wed Jul 3 12:27:38 UTC 2013


On Wed, Jul 3, 2013 at 8:43 AM, Jeremy Jongepier <jeremy at autostatic.com>wrote:

> On 07/03/2013 12:19 AM, Harry van Haaren wrote:
> Nice article Harry! Some remarks though:
> * Is /dev/rtc the kernel timer? I thought it was the device node for
> access to the real-time clock. I don't even think it's necessary to
> prioritize it anymore because most applications use the kernel timer:
> http://wiki.linuxaudio.org/wiki/system_configuration#hardware_timers
> I'm far from an expert on timers so I could be wrong, I still find this
> a bit of esoteric stuff.
>
Same here: I wrote that because its in my setup, and AFAIK its the kernel
timer... Just found this article:
https://www.kernel.org/doc/Documentation/rtc.txt   It suggests that
/dev/rtc is the "old" RTC, and /dev/rtc0 /dev/rtc1 .. rtcX is the new
system. I have got /dev/rtc0 present on my system. I'll investigate into
whether JACK / the ALSA backend use /dev/rtc, or if it really isn't used
anymore.


> * Using setpci in this context is deprecated unless you're still using
> am machine with a PCI bus which I highly doubt:
> http://wiki.linuxaudio.org/wiki/system_configuration#pci_bus_latency
>
I was advised on IRC that the PCI bandwidth reset would help, and it didn't
negatively influence my machine: hence I added it.

lspci -v -t shows that my firewire, cardbus ("CardBus bridge: Texas
Instruments PCIxx12 Cardbus Controller")  SD card and multimedia card
readers are on the same branch, connected to the root node. I suppose
rm-modding those kernel modules would ensure better performance (not using
them probably suffices).

The graphics chip is on its own node, also connected directly to the root.
I don't think it'll get in the way.. Setting the latencies won't hurt, I'll
leave it there for now but add a note that on modern hardware its not
necessary.

Thanks for the feedback! -Harry
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