Embedded Linux Primer

More good stuff from Linux Audio Users. This was a reply by Paul Davis to a query about PCI latency.


> If anyone else has been down this road and knows of how to solve the
> underlying issues (sata hard disk interrupts taking up too much PCI
> bandwidth), I am still searching for an answer and I’m VERY interested
> in hearing something from you.

i didn't write the original version of this, but you might find it
useful. use it as normal system startup script (how to do this varies
depending on your distro, but probably involves /etc/rc.d/init.d)

#!/bin/sh

case $1 in

From my dabbling in the world of Linux audio, I've discovered that using ulimit(s) you can grant real time privileges to a non-root process.

This link describes the steps necessary!
Realtime Scheduling for Non-root Users

From my dabblings in Linux Audio, I've come across this nice script written by Rui Nuno Capela. Together with a config file that you can customize, you can use this script at boot time to adjust the priorities of various threads (including kernel threads) that have been created. Of course, you need to be using CONFIG_PREEMPT_RT for this to work.

If you decide to try it out, post your results (or anything you may learn about its use) here. Thanks!

You can find the script and config file here:

I bought "embedded Linux Primer" and read chapters 4 and 16. To build kernel source tree using command line as

make ARCH=ppc CROSS_COMPILE=ppc_85xx mpc8540_ads_defconfig

and compile a linux kernel for ppc.
make ARCH=ppc CROSS_COMPILE=ppc_82xx uImage

My question is how do I know I should use ppc_85xx and ppc_82xx?

----henry zhang

This complex topic is introduced in this wikipedia page:

http://en.wikipedia.org/wiki/RCU

Here is a good article explaining real time concepts and issues relating to the -rt patchset and the CONFIG_PREEMPT_RT mode of the Linux kernel:

http://www.linuxjournal.com/article/9361