xp sp3 dev mgr shows4 cpu's only uses 1

September 22, 2010 at 11:09:34
Specs: Windows XP
using xp ap3 on nwq HP Pavilion elite because wn7 is very flaky. but new I5-650 cpu is not being fully used by xp, although dev mgr shows 4 cpu's, apparently only1 thread is being used, as indicated by task manager.

googling shows lots of folks showing 2 or 4 cpu''s in task manager.

a realtime test shows Microsoft security essentials using up to 95% of cpu in xp, while less than 30% in win7.

appreciate any help,


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September 22, 2010 at 12:43:05
There is a lot to understand about cpu utilization.

One of the first aspects you have to consider is the correct vocabulary. A thread is a part of a program that can be executed independently.

What you see when looking at a CPU counter is not a thread but CPU % utilization.

Using multiple cpu's is a result of programming a program to be multithreaded. Being multithreaded allows the system [combination of OS and hardware] to allocated threads to other CPUs during the programs execution.

None of this is within any control you have over the OS or hardware. There is nothing to help you with in this case.

Best of luck.

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September 22, 2010 at 12:59:29
jperhaps there is some misunderstanding of my brief description of the prob.

my I5 cpu is defnied as having 2 cores, and FOUR threads, in Win7.
byt in XP, it is defined as 1 core and 1 thread.
so obviously xp is not fully utilizing the cpu.
but google shows that many folks DO get multiple cpu''s showing in task manager.

but the device manager in XP does show FOUR cpu's.

and I have read that XP itself DOES utilize dual core cpu's, even if individual programs do not.

your last statment that the user has no control over dual processing also is inaccurate from my understanding.
there is an AFFINITY setting that can be used to allocate specific cores/thresds to a particular program, etc.

perhaps someone else will have a solution.

thanks for replying,


so WHY

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September 22, 2010 at 13:21:06
The affinity option in Task Manager restricts a process to using only specified cores. But be aware that this is not an exclusive allocation. The system can, and will, use the cores specified this way for other processes as it sees fit. Setting affinity is rarely useful and more often than not it will impair performance. The setting is really more useful for testing purposes than as a means to improving performance.

To be sure, you can find numerous articles on the internet describing how setting affinity will improve performance. But they are based on a very warped understanding of how thread scheduling works. In the large majority of cases you will be best served by letting Windows manage system resources as it sees fit.

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September 22, 2010 at 15:21:58
"my I5 cpu is defnied as having 2 cores, and FOUR threads, in Win7.
byt in XP, it is defined as 1 core and 1 thread. "

If you look at the chip specs it says 2 cores and 4 threads. Threads in this case refer to hyperthreading which is a subset of symmetric multiprocessing.

This is NOT what you see when you bring up task manage. You don't see any graphic showing of threads. You do see how many threads under "system" under the performance tab.

You are mixing concepts of hardware with software utilization.

I seem to recall XP HOME does not support multiprocessing. Sounds like this is your xp issue.

Setting a program affinity to a cpu has nothing to do with multithreaded programing.

In most situations, all setting affinity does is say "you single threaded program use this cpu"

After all if the program was multithreaded you would not need to set affinity except in the case of servers where you have many cpus and you want multithreaded programs like SQL Server to user processors 2-4 instead of 0-1 so sql processes don't compete with OS cpu processes.

All single threaded apps run on processor 0 by default.

There isnt' anything here for you to fix.

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