Re: Detecting CPUs and cores

Patricia Shanahan wrote:
A programmer may have determined experimentally that two threads running
on different cores get significantly more throughput than one, but that
the same two threads running hyper-threaded get less throughput than
one. The program is written so that the number of threads is a free
parameter.

The program should limit the number of threads to be no more than the
number of cores, but cannot because it cannot tell the difference
between two separate cores and a single hyper-threaded core.

It is likely that the two hyper-threaded cores will achieve more throughput than on one of those "cores". The reason Intel provided hyperthreading is that it increases throughput on the chip.

--
Lew
.

Relevant Pages

  • Re: Detecting CPUs and cores
    ... the same two threads running hyper-threaded get less throughput than ... number of cores, but cannot because it cannot tell the difference ... I haven't personally benchmarked the effect of Hyper-Threading but, if your application is relying on the result of availableProcessorsto fine tune it's concurrency strategy, it's important to be aware that 1 HT CPU may behave quite differently from 1 dual-core CPU. ...
    (comp.lang.java.programmer)
  • Re: Detecting CPUs and cores
    ... throughput than on one of those "cores". ... The reason Intel provided hyperthreading is that it increases throughput on the chip. ...
    (comp.lang.java.programmer)
  • Re: Detecting CPUs and cores
    ... Lew wrote: ... the same two threads running hyper-threaded get less throughput than ... number of cores, but cannot because it cannot tell the difference ... benchmarks that they simulate during processor design. ...
    (comp.lang.java.programmer)
  • Re: Detecting CPUs and cores
    ... of them is far more involved than simply counting cores or chips. ... You need to get into the architecture of what's shared and what ... A programmer may have determined experimentally that two threads running ... the same two threads running hyper-threaded get less throughput than ...
    (comp.lang.java.programmer)
  • Re: processors of the future: super-computer-on-a-chip?
    ... " How many cores do you think a chip could have, lets say 10 or 20+ years from now? ... relegating single-threaded performance to the back seat of its POWER architecture: instead, after pioneering dual-core products 5 years ago it has been steadily improving their single-threaded performance. ... Sure, there will be a few applications that could make really good use of huge numbers of slower cores, but will they fund the associated development sufficiently to overcome the resources available to develop commodity products? ... [end quote] ...
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