memcpy performance regressions 2.19 -> 2.24(5)

[H.J. Lu]

On Mon, May 22, 2017 at 6:23 PM, Erich Elsen <eriche@google.com> wrote:
> I definitely think increasing the size in the case of processors with
> a large number of cores makes sense.  Hopefully with some testing we
> can confirm it is a net win and/or find a more empirical number.
>
> Thanks for that patch with the tunable support.  I've just put a
> similar patch in review for sharing right now.  It adds support in the
> case that HAVE_TUNABLES isn't defined like the similar code in arena.c
>  and also makes a minor change that turns init_cacheinfo into a
> init_cacheinfo_impl (a hidden callable).  init_cacheinfo is now a
> constructor that just calls the impl and passes the cpu_features
> struct.  This is useful in that it makes the code a bit more modular
> (something that we'll need to be able to test this internally).

This sounds a good idea.  I'd also like to add tunable support in
init_cpu_features to turn on/off CPU features.   non_temporal_threshold
will be one of them.


-- 
H.J.