[LLVMdev] On LLD performance

[Davide Italiano]

On Mon, Mar 16, 2015 at 1:54 AM, Davide Italiano <davide at freebsd.org> wrote:
>
> Shankar's parallel for per-se didn't introduce any performance benefit
> (or regression).
> If the change I propose is safe, I would like to see Shankar's change
> in (and this on top of it).
> I have other related changes coming next, but I would like to tackle
> them one at a time.
>

Here's an update.

After http://reviews.llvm.org/D8372 , I updated the profiling data.

https://people.freebsd.org/~davide/llvm/lld-03162015.svg
It seems now 85% of CPU time is spent inside
FileArchive::buildTableOfContents().
In particular, 35% of the samples are spent inserting into
unordered_map, so there's maybe something we can do differently there
(e.g. , Rui's proposal of a concurrent map doesn't seem that bad).

Thanks,

-- 
Davide

"There are no solved problems; there are only problems that are more
or less solved" -- Henri Poincare