Re: [PATCH v2 0/3] RISC-V: ifunced memcpy using new kernel hwprobe interface

[Jeff Law <jeffreyalaw@gmail.com>]

On 3/30/23 12:43, Evan Green wrote:
> On Wed, Mar 29, 2023 at 11:20 PM Jeff Law <jeffreyalaw@gmail.com> wrote:
>>
>>
>>
>> On 3/29/23 13:45, Palmer Dabbelt wrote:
>>
>>> It's not in for-next yet, but various patch sets / proposals have been
>>> on the lists for a few months and it seems like discussion on the kernel
>>> side has pretty much died down.  That's why I was pinging the glibc side
>>> of things, if anyone here has comments on the interface then it's time
>>> to chime in.  If there's no comments then we're likely to end up with
>>> this in the next release (so queue into for-next soon, Linus' master in
>>> a month or so).
>> Right.  And I've suggested that we at least try to settle on the various
>> mem* and str* implementations independently of the kernel->glibc
>> interface question.
> 
> This works for me. As we talked about off-list, this series cleaves
> pretty cleanly. One option would be to take this series now(ish,
> whenever the kernel series lands), then cleave off my memcpy and
> replace it with Vrull's when it's ready. The hope being that two
> incremental improvements go faster than waiting to try and land
> everything perfectly all at once.
No idea at this point if VRULL's is better or worse ;-)  Right now I'm 
focused on their cboz implementation of memset.  Assuming no uarch 
quirks it should be a slam dunk.  But of course there's a quirk in our 
uarch, so testing testing testing.

I did just spend a fair amount of time in the hottest path of their 
strcmp.  It seems quite reasonable.

Jeff