clipka <ano### [at] anonymousorg> wrote:
> Am 06.08.2014 11:20, schrieb Le_Forgeron:
> > Le 06/08/2014 10:45, clipka a écrit :
> >> Must be a high-core-count thing; on my 4-core i7, running Windows 7, I
> >> see this for a random scene:
> >
> >  From my point of view, it's a "use less than 50% of resources" thing.
> > The graph goes up to 40 threads, but the guy has 80 possible cores ( 40
> > true (4 x 10), x 2 by HT).
> >
> > The curves past 40 threads are only extension of points below 40. there
> > is not even a data point at 50, 60 or 70, when Xeon are used. All 40+
> > points are with Opteron (and there is no HT in Opteron... it's
> > different, Intel HT and AMD module are not the same)
> >
> > Opteron cores' count is 48 (4 x cpu, 2 dies of 3 piledriver module each,
> > each module providing 2 execution thread (core), 24 modules.
>
> jhu correctly points to the table at the bottom:
>
> ---------------------------------------------------------------------
> Selected data points showing effect of Hyper-Threading
>
> Threads | Linux HT off | Linux HT on | Windows HT off | Windows HT on
> --------|--------------|-------------|----------------|--------------
>   40     | 40 sec       | 40 sec      | 53 sec         | 79 sec
>   60     | 39 sec       | 35 sec      | 50 sec         | 78 sec
>   80     | 39 sec       | 32 sec      | 50 sec         | 78 sec
> ---------------------------------------------------------------------
>
> If it was a matter of 40 threads being poorly distributed among physical
> and virtual cores, you'd expect /some/ improvement when going to 80
> threads, but apparently there is /no/ noteworthy difference whatsoever.

Is the official Windows binary compiled with Microsoft's compiler or Intel's
compiler?

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