Intel D525MW Latency issues

Hi,
Got the Intel D525MW, (Actually got the D525MWV, in the hopes of eventually going direct lvds).
Did a fresh install of the latest 10.04, which went well.
Latency test is much worse than the reported values I see posted here.
Starts out great, at about 6 microseconds in each thread. After about 5 minutes I'm up to 9 microseconds or so. However If I run for half an hour, and stress it a bit, I end up with 29 uS on the fast thread, and 10 or 11 on the servo thread. There don't seem to be many bios options to disable on this card. I don't have anything hooked up yet but CD and HD.
I shouldn't have to recompile anything and disable SMI support should I? I don't have the system here at work, but thought I had seen something to disable MMX support, which I did on the first Bios page, but other than that, I left it as it arrived. The machine I'm working on actually never does any coordinated moves, ( no circles or diagonals ) so the whole issue may be academic.

Thanks for any insight.
lm

Here are a few things I did:

Disable Hyper-threading in the bios, and anything else that is not really needed
Do A/B testing on the bios parts some seem to help others not

Limit the system to 1 processor core: wiki.linuxcnc.org/cgi-bin/emcinfo.pl?The..._Parameter_And_GRUB2

Turn off all power management, screensavers etc.

I also went in and shutdown a lot of the unnecessary start up items (Bluetooth etc).

I think when I was done I have it down to a lil under 7500 while opening and closing PDF's
(I was surprised how much they affected the latency) and running the various screensavers.



Hope this helps

Well, I've done a bunch more tests, and have come to the following conclusions:
With hyperthreading disabled:
7 microseconds of jitter is optimistic, and isn't realistic under stress. Running latency test for a few hours while doing a variety of other applications will result in 12 microseconds max. pretty consistently.
You can run overnight with no applications running and it will stay at 7 microseconds or less, but that value won't hold up under stress.
With hyperthreading enabled in the BIOS:
You can let the system run overnight with nothing but latency test running, and you will find jitter values in the 25 microsecond range. Twice as bad as without hyperthreading, and with no stress. Stressing the system doesn't seem to increase this value too much though. Interesting that the system monitor reports 2 cores with hyperthreading off, but 4 cores with it on.
The board seems stable and sure runs cool. I think it will be a good platform.

Hi

Thanks for sharing your results, 12,000 is a good real world latency, very usable.

It also shows the importance of stressing the system, not just running the latency tester and taking the figure returned as being correct.

Did you try the isolcpus boot parameter?

John Thornton recommends this plus disabling of hyperthreading for the 525 boards, it would be interesting to see if this had a significant effect both in isolation and in combination with the disabling of hyperthreading.

This link perhaps provides the fullest guide to implementing
wiki.linuxcnc.org/emcinfo.pl?The_Isolcpu..._Parameter_And_GRUB2

This one relates to the use of the previous 510 board with Ubuntu 9.10 and a rebuilt system, but shows a perhaps simpler way of incorporating the kernel parameter into grub.conf
wiki.linuxcnc.org/emcinfo.pl?EMC_Ubuntu91

The introduction of GRUB2 certainly complicates matters and is symptomatic of Ubuntu version number chasing, resulting in technical superiority triumphing over usability.

Because I have so many different operating systems and versions on my development/simulation computer at any one time, I have a small install of 8.04, which uses GRUB1, solely as a maintainance install.
This is the only OS install which has grub on it and which can access the MBR of my second HDD which I boot from.

Whenever I build a new kernel or install another distro etc. I alter the /boot/grub/menu.lst on this maintainance install and run grub-install from there.

That way if the new kernel / system does not work, I just boot to something else and try again.
I never get my MBR wiped by a badly behaved install which then locks me out because it cannot boot.

Not a solution for the average workshop CNC computer, but if you have 4 HDDs and about 30 logical volumes, a very easy way to help prevent total screw up!

regards

I went down this morning to confirm my numbers

I turned on the PC and let it sit idle for about 4 hours.

Upon initial turn on it is about 1900, 4hrs later in the 4000s

Upon running opening and closing the web browsed, screen savers
and PDF's (PDF's cause the biggest change for me) it is as 7086.

I will let it run and check it again later.


When I first started tuning my system my numbers were much higher.

You may also want to load the latest BIOS updates (Mine was a few revs behind.)

Well I finally was able to get it up to almost 12000

I had to enable random screen savers and just let them run
(I normally just have the screen go blank.)


My machine only runs at rapids of 24 ipm so it really should not make a difference

ArcEye,
No I haven't tried the isolcpus parameter. I haven't successfully re-made the system, but thought I ought to get familiar with the tools available, so the other day I used apt-get, and loaded up a bunch of tools. When I tried to make the system, it failed with some dependency missing. I forget what it was right now, and got sidetracked.
I think I need to start out a little smaller, but past the 'hello, world'.
Harry_Y,
I'll check the Intel web site for the latest BIOS version. Mine might be a bit out of date too. Also, since I bought the version with LVDS support, there might be more going on in the background.
I figured it was important to stress the system. It isn't going to crash on the simple jobs. It's going to crash on that 4 hour contouring job where the operator is really bored and starts playing games when there's 2 hours between tool changes. (and good restart points)
lm

I run my systems pretty stripped, if it does not need to be there I try
to remove it, that way it is less things that can interfere with EMC.

I have to work pretty hard to get high latency numbers

How I actually run my system it is only EMC running
(and background processes) no Games, no surfing
the web no screen savers, etc.

It only has one function, to run the machines.

I also pad my Latency numbers to give the system some headroom

My system is quite small and simple in comparison to others
and I am by no means an expert, I am still a beginner with EMC.

Your testing has prompted me to re look at a few things here

Good Luck, and thank you.

I got my Intel D525MW running today, with HT off and isolcpus=1 I got it up to 12.5 & 16µs from it with glxgears and screen saver preview running and when opening a pdf and maybe there was a browser open too.. It was running 4-5 hours or so without that pdf-thing.

Now it was 4.6 & 5.5µs after ~2hours idle and didn't change when opened a pdf.

I'm using Mesa 5i20, so it should be quite ok..