Re: Increase WinXP/jre CPU usage?
Chris Uppal wrote:
Arne Vajh?j wrote:
No it is single core.
BUT it has hyperthreading.
Which in WinXP task manager looks like 2 CPU's !
And to utilize HT you still need to multithread.
But don't assume that making the application use the other "cpu" will
necessarily speed anything up. HT is (for most purposes) better regarded as a
cheap marketing gimmick than a valid technology.
Or -- to put it another way -- the CPU usage reported by TaskManager is
misleading. It suggests that 50% of your available horse-power is
unused. My bet would be that it's more like 5% -- if not actually zero.
Here's a suggestion for a cheap test:
1. Add, if the application does not already contain it, some performance
statistics collection keeping track of how much elapsed time it takes to
do a given quantity of the compute intensive work.
2. Run one copy of the application. Record the statistics.
3. Run two copies of the application, simultaneously. Record the statistics.
If it is likely to benefit from multi-threading, the total work rate
will be significantly higher with two copies than with one. If it is the
sort of case Chris is talking about, each copy will run at slightly
better than half the speed of the single copy.
This test automatically takes into account questions such as how much
time a thread of your application spends waiting for memory, which can
affect how much you gain from hyperthreading.
Patricia