Can't find "menu.lst" for adding "isolcpus 2,3"

Another newbie here. I am trying to run Linuxcnc 2.5? on 10.4 and am getting a LOT of jitter on the latency test. Lucky for me I just upgraded my system to an AMD Phenom X4 with 4gb of memory on an ASUS M2A-VM Green motherboard. Also, I am expecting a new XFX AMD Radeon HD 5450 1GB GDDR3 PCI-Express Video Card to arrive today to replace an older video card. Now I find out that to reduce jitter the term " isolcpus 2,3" needs to be added to the kernel in "boot/grub.menu.lst" It's all Greek to me because I'm new to Linux, but I can't seem to find the "menu.lst" file anywhere on my PC. I've followed directories, searched the system, and read the instructions but am at a dead end. I'm trying to accomplish:

For computers using classic GRUB as the boot manager, this is accomplished by editing the file /boot/grub/menu.lst to include the boot parameter "isolcpus=1" (for example) at the end of appropriate kernel lines.

as in the instructions on:

wiki.linuxcnc.org/cgi-bin/wiki.pl?The_Is..._Parameter_And_GRUB2

Where am I going wrong?

Hi

You are using 10.04 which uses GRUB2, so you are following the wrong instructions.

You want the section starting at this para

As shipped, Ubuntu distributions using GRUB2 include a set of configuration script files in the directory /etc/grub.d/ with names 00_header, 05_debian_theme, 10_linux, etc. These files are processed in numerical order as a component of GRUB2 creates the file grub.cfg. Kent's solution is to add to this directory a new file 07_rtai that scans for linux-rtai kernels and for them only creates boot menu entries including the "isolcpus=1" parameter. Kent uploaded a copy of this file at 07_rtai.

Now I find out that to reduce jitter the term " isolcpus 2,3"

Why are you turning off CPUs 3 and 4 of what is presumably a 4 core processor?

I would have thought isolcpus=1,2,3 would have been better ( the cores are numbered from 0) unless you have some specific advice for your particular machine and chipset.

Also, I am expecting a new XFX AMD Radeon HD 5450 1GB GDDR3 PCI-Express Video Card to arrive today to replace an older video card

I am sure it will be better at graphics than your old one, but there is no guarantee that it will be low latency
You should not use the proprietary drivers with this until you test latency so you can compare the opensource and the proprietary ones.
You may find the latter are far worse for latency.

regards

Thanks, ArcEye. I found the correct files in the correct folder. I will load the 07_RTIA file if I can figure out why it won't let me add a file to the directory. It sez that since I am not the owner, I can't do squat. Still working on that. The folder is owned by "root" and I'm not "root"(?).

Open a terminal and do sudo whateverapplicationname
and you will be running it as root

Big improvement!!Still haven't been able to isolate core 2 & 3 yet, but just adding the new video card dropped the latency from over 200,000 down to about 13,000. Right now it's running:

1. glxgears
2. Big brother 16 Live Feed
3. a 6.5 gb copy of a photo folder from a networked PC
4. Smartdrive test on main system drive
5. Opening Firefox & closing

and the max jitter recorded is 21,945. Will continue to try to isolate cores 2 & 3 (because that's what was recommended in the documentation) to see if there is any jitter improvement. Anyone know of any tricks in running a HobbyCNC driver board with LinuxCNC? I'll have eStop on pin 10, Xstops on pin 11, Ystops on pin12, Zstops on pin 13, and am using pin 1 to control a low vdc coiled, solid state relay to turn power on and off to my 115VAC spindle motor.

Still going well... Reset the statistics and then ran for another 3 hours in the same configuration with a max jitter of 10,594 on the 25us scale. Maybe I won't have to isolate some of the CPUs.

10K is perfectly good for software stepping, I would stop there.
It was obviously your onboard video.

Shutting down CPUs does affect overall performance.

2. Big brother 16 Live Feed

I hope this was a surveillance camera not the god awful TV program