Re: Detecting CPUs and cores
Daniel Dyer wrote:
What's slightly less helpful is that my Windows PC at work returns 2
from availableProcessors() despite the fact that it is single-core,
albeit with Intel's Hyper-Threading.
That's not Window's nor Java's fault. The HT processor is electrically
equivalent to two CPUs to the rest of the system. So are multi-core CPUs.
Here's the $64,000 question - what is the value of knowing the number of dies
on which the cores reside? A "core" /is/ a CPU as far as any practical use of
it goes; same for the two virtual cores seen in a HyperThreaded processor.
You program them in every respect as if they were completely separate; the
fact that they happen to share some real estate couldn't be less relevant.
A difference that makes no difference is no difference.
--
Lew
.
Relevant Pages
- Re: Performance improvement using X5355 over 5080
... would expect to get by swapping 2 x Xeon 5080 3.73GHz Dual-Core CPUs with 2 x Xeon X5355 2.66GHz Quad-Core CPUs? ... you are trading two cores which are 40% faster, ... And at time when you have load, but ony a few threads running, you lose, even if you win under max load. ...
(comp.sys.intel) - Re: Performance improvement using X5355 over 5080
... would expect to get by swapping 2 x Xeon 5080 3.73GHz Dual-Core CPUs ... 40% faster, for four cores. ... And at time when you have load, ...
(comp.sys.intel) - Re: Intel details future Larrabee graphics chip
... for dinky little SMP systems of 4-8 cores. ... Why multi-thread *anything* when hundreds or thousands of CPUs are ... video CPUs using fancy memory and generics doing the grunt work. ... Duo, and never get trojans, memory leaks, any of that. ...
(sci.electronics.design) - Re: The machdep.hyperthreading_allowed & ULE weirdness in 7.1
... I have a single-CPU system with P4 HTT-enabled processor, ... For 4BSD, which uses a "pull" model to bring work from work queues, this means that CPUs will go to sleep and remain that way unless they're actively receiving interrupts. ... The only reliable way to disable hyperthreading is to do so using your BIOS setting, or use loader.conf to disable probing of the pics on unwanted cores, which will cause the CPUs not to be enumerated and hence not used. ... You could imagine teaching ULE about policies such as "Don't use HTT cores", or perhaps just cpuset about those policies. ...
(freebsd-stable) - Re: The machdep.hyperthreading_allowed & ULE weirdness in 7.1
... I have a single-CPU system with P4 HTT-enabled processor, ... For 4BSD, which uses a "pull" model to bring work from work queues, this means that CPUs will go to sleep and remain that way unless they're actively receiving interrupts. ... The only reliable way to disable hyperthreading is to do so using your BIOS setting, or use loader.conf to disable probing of the pics on unwanted cores, which will cause the CPUs not to be enumerated and hence not used. ... You could imagine teaching ULE about policies such as "Don't use HTT cores", or perhaps just cpuset about those policies. ...
(freebsd-current) |
|
