Improving my latency figures

[greybeard]

I've found that each time I start my latency test I get quite a wide range of jitter figures, even before I start to load the cpu.
With figures that can vary from 23000 to 100000, I've tried to work out why it varies so much, but can't find much information that I can understand

The system I run is Gigabyte GA-5AX mobo, with AMD K-6/500Mhz, 512Mb RAM, ATI C1-8M video card, Seagate 20Gb hdd, partitioned with 4Gb root/4Gb home/1024Mb swap, and leaving the rest free.

I've found the general suggestion to "disable" everything you can in bios, but no specific instructions.
Is it really a case of change one thing, then run a latency test, and if it's worse reverse the change, or is there a more logical way to approach the problem ?

I'm not looking for a BDI, but at least something like a flowchart approach that might get me moving motors if not producing chips.


Many thanks for your time,
John

[jbcj]

I had newer boards that were giving me numbers in the same range. I ended up purchasing an old intel board with a 2.8 Gig pentium 4 without all of the newer CPU and power functions and I am down under 10,000. Cost for the whole system with linux loaded $50.00. I think old iron is better for this... Take the Bootable CD to flea markets and used computer store see if they will let you load and run a test for 20 min....

Jim

[acondit]

A very common cause of latency problems is the video. Many on board videos are particularly bad but some video cards are also atrocious. So if you have another video card available, you might swap video cards to see if that helps.

Alan

[greybeard]

Hi guys, and thanks for your thoughts.

I took the coward's way out, and re-built the whole system.

I'd got another desktop set up to use as a dedicated graphics centre for all our printing needs, so I switched the hdds over and immediately got latency figures down in the 10-20K region.
So a major swap round of all the old desktops, and I think I'm in business, one graphics centre, one machine centre, and a pile of bits that may become a back up for either or both.

I still think there is a need for some sort of logical approach to be formulated, if only to help newbies like myself.
For instance, a description of how a particular type of hardware affects the overall latency, or what its contribution to a system is, in the way it affects other hardware.

Regards
John

[pminmo]

Smart move, a motherboard/500mhz K-6 probably won't get there regardles of video setup. Most times latency resides with the MB/video combo. If the video is on the MB then a cheap video card can potentially fix it. But somethimes it's an inefficient bios that has too much code in the interrupt handling. SMI is particularly problematic becuse it's a non maskable interrupt and has to execute bios code.

[jgro]

I had problems with latency also. My fix...I installed Xubuntu and then loaded EMC. The problems went away.

jgro