WinXP P95 slowdown
 

I am running P95 23.6 on a Dell 2.4GHz P4 running WinXP home edition, getting cycle times of 0.347 for a 10M digit exponent. I notice 2 things:

1) the system thread (not system idle process) is taking 60-95% of the CPU time much of the time, even when nothing else is happening on the machine. I have increased priority to 4 with no effect on iteration times or %CPU time that goes to P95.

2) Prime 95 itself is very unresponsive. Menus take seconds to open, it can take up a second for a typed char to appear in an input box, etc.

Any ideas of why this is going on?

With your setup as described, your expected iteration time would be 0.025 sec.

To state the obvious, something else on your machine is using up a lot of CPU time. Try rebooting and update your anti-virus and anti-spyware software. Make sure you turn on the firewall built into Windows XP (it may be off by default).

[QUOTE][i]Originally posted by GP2 [/i]
[B]With your setup as described, your expected iteration time would be 0.025 sec.[/B][/QUOTE]

I think (s)he is referring to 10M digit numbers, i.e. 1792K FFTs. The iteration time should in that case be between 0,090 and 0,100ms.
Anyway, it´s indeed obvious that something is stealing lots of CPU cycles. Try running a program that gives a full description of the programs and associated processes running in the system (I usually recommend TaskInfo). You may be having a virus or spyware problem...:ermm:

Ran TaskInfo. P95 is getting 20% and System Process is getting 75%. There are many threads under System, all called thread, and the last thread in the list appears briefly, sucks up all the cycles, and disappears again.

Not sure what to do with that info, I am afraid. There is no obvious foreign task that I could uninstall.

What happens when you manually kill those threads?

Maybe you could take a screen shot of your task manager for us to see?

can't kill the thread - they disappear within 2 secs on their own and then a new one appears. All Task Man shows is System process with 98% CPU usage.

Here is a screen shot from Task Info - all these threads are under System (35 total) and the bottom one is the CPU hog.

Did you make sure the machine was patched against all active worms (Blaster, etc) [B]before[/] you connected it to a network with other machines running Windows? If not, even if it was just for a few seconds (usualy takes less than a minute to catch one), reinstall Windows and install all current patches from CD before you connect it to the net again. Your computer is probably busy spreading worms.

Do you have an antivirus running?

Yes, McAfee is running.

Have ou visited [url=http://windowsupdate.microsoft.com/]Windows Update[/url] to make sure your machine has all the latest security patches from Microsoft?

Yup, I have, thanks. Pretty much have done all the easy stuff, uninstalled anything I didnt recognize, run a virus scan. It picked up a Trojan, but deleting the files didnt change anything and now the scan is clean but the slowdown remains. Ran Scandisk. Would run msconfig, but cant find it in Win XP.