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Re: Ping: [Patch] aarch64: Thunderx specific memcpy and memmove
On Thu, May 25, 2017 at 5:28 PM, Andrew Pinski <pinskia@gmail.com> wrote:
> On Wed, May 24, 2017 at 11:42 PM, Siddhesh Poyarekar
> <siddhesh@gotplt.org> wrote:
>> On Wednesday 24 May 2017 10:34 PM, Szabolcs Nagy wrote:
>>> - i don't know if you plan to make more changes to the thunderx
>>> memcpy, if prefetching is the only change then it's likely that
>>> we can agree on a generic version that's good enough. if you
>>> do plan to make further changes, then keep in mind that we try
>>> to have same/similar generic memcpy across c runtimes and if
>>> your change is good for generic we might not be able to use the
>>> code outside of glibc (so newlib, bionic, freebsd,.. memcpy
>>> would diverge)
>>
>> Steve, if that is desirable then please consider contributing the code
>> to cortex-strings[1].
>
> One memcpy does not fit all micro-arch. Just look at x86, where they
> have many different versions and even do selection based on cache size
> (see the current discussion about the memcpy regression).
No it doesn't but that's not an excuse for putting in multiple copies without
the engineering to see if generic memcpy's are improved. Otherwise it's
just bloatware.
regards
Ramana