crazy WinXP scheduling

[stippix]

Hi everybody!

I am new to this forum, so ...

My question is about prime95 stress testing:
I have a duallie (Athlon XP 1800+, non-modded) running WinXP SP1 and if I start two stress testing instances every gets 50% of the system - so one instance pro cpu. Everything okay!

But if I start 4 instances then I would expect every instance at 25% of the systems resources.
Mostly this happens - but sometimes I get one instance taking 40% and every other only 20%, or so.
Once it was very extreme: one got 50% and every other only 17% of the system.

I think the scheduling of WinXP pro is not so perfect ...
Any suggestions why this is happening?

(Of course I know I could set affinities in Windows TaskManager

P.S.:
This problem is not only occurring with prime but also if I am starting SMPOV with 3 or more instances in order to run multithreaded POVray renderings.

greetings stippix

 

[VirtualLarry]

Originally posted by: stippix
Hi everybody!

I am new to this forum, so ...

My question is about prime95 stress testing:
I have a duallie (Athlon XP 1800+, non-modded) running WinXP SP1 and if I start two stress testing instances every gets 50% of the system - so one instance pro cpu. Everything okay!

But if I start 4 instances then I would expect every instance at 25% of the systems resources.
Mostly this happens - but sometimes I get one instance taking 40% and every other only 20%, or so.
Once it was very extreme: one got 50% and every other only 17% of the system.

I think the scheduling of WinXP pro is not so perfect ...
Any suggestions why this is happening?

(Of course I know I could set affinities in Windows TaskManager

P.S.:
This problem is not only occurring with prime but also if I am starting SMPOV with 3 or more instances in order to run multithreaded POVray renderings.

greetings stippix

Yes, the process scheduling or interrupt-handling, or *something* in XP is severely b0rked.

I recently discovered, that I cannot use my external serial-port hardware modem, under XP SP1, at the same time that I am defragmenting a HD in my system. That's ridiculous. I have no idea what the actual problem is, but I know that there are a number of kernel hotfixes for XP, here's hoping that they get included in XP SP2.

Btw, there's absolutely no problem using same hardware, in Win98se nor in W2K SP2. So it must be a software issue with XP somehow.