[PATCH 0/2] Multiarch hooks for memcpy variants

[Wilco Dijkstra]

Zack Weinberg wrote:
>
> Last time we had this argument, someone (Ondrej?) claimed that the
> overhead of going through an ifunc for intra-libc calls (specifically
> to memcpy, IIRC) was dwarfed by the I-cache costs of having both the
> generic and the targeted version of the function get used. I would
> really like to see measurements addressing that specific point.

I think it might be more easily measured if we make the effect much worse,
for example by adding several KB of NOPs at entry of generic memcpy.

I could easily generate a trace of internal calls to memcpy, however the key
question is which functions in GLIBC use memcpy in performance critical
ways and which applications make heavy use of those?

Wilco