Re: [PATCH] aarch64: optimized memcpy implementation for thunderx2

[Siddhesh Poyarekar <siddhesh at gotplt dot org>]

Hi!

This seems like your first contribution to glibc, Welcome!  Can you (or 
one of the stewards) please let us know if you have signed the FSF 
copyright assignment for glibc?  That is necessary for any contributions 
to be included into glibc.  In general, please review the Contribution 
Checklist[1] to understand the prerequisites for contributing patches to 
glibc.

On 28/09/18 11:38 PM, Anton Youdkevitch wrote:
> Optimized memcpy implementation using "ext" instruction. The
> speedup is up to 30% on larger lengths comparing to the existing
> thunderx2 implementation. Performance comparison is done using
> the standard lib's benchmarks.

Could you please name the microbenchmarks you've used to make the 
comparison.  That is, have you checked memcpy-large or memcpy-walk? 
Given that typically large copies are uncached, I would trust 
memcpy-walk more than memcpy-large for them because in the latter case 
the instruction costs will tend to dominate over the cost of load from 
memory, which is not very useful for large copies.

Also, (and this is a personal nit so you don't have to take it 
seriously) it would be really nice if the patch is inline and not an 
attachment since that allows me to respond to the patch contents inline :)

Thanks,
Siddhesh

[1] https://sourceware.org/glibc/wiki/Contribution%20checklist