[llvm-dev] LLD: time to enable --threads by default

[Renato Golin via llvm-dev]

On 17 November 2016 at 17:50, Mehdi Amini via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> It depends on the use-case: with ThinLTO we scale linearly with the number
> of physical cores. When you get over the number of physical cores you still
> get some improvements, but that’s no longer linear.

Indeed, in HT, cores have two execution units on the same cache/bus
line, so memory access is likely to be contrived. Linkers are memory
hungry, which add to the I/O bottleneck which makes most of the gain
disappear. :)

Furthermore, the FP unit is also shared among the ALUs, so
FP-intensive code does not make good use of HT. Not the case, here,
though.

cheers,
-renato