lstrncpy_from_user() additional question [Was: [parisc-linux] test case for pa_memset() ;-)]

lstrncpy_from_user() additional question [Was: [parisc-linux] test case for pa_memset() ;-)]

[Joel Soete]

Randolph,

I would like to get your opinion about the idea to re-write this lstrncpy_from_user() in c as you did with pa_memcpy() (may be 
easiest to maintain?)

Thanks,
	Joel


Randolph Chung wrote:
>>Any interest?
>>
>>This tmset3.c is a very draft and all advise will be welcome :-)
> 
> 
> Joel, i didn't notice earlier that you were working on memset.... i
> don't think you'll see much improvement over our current implementation.
> memcpy was a target for optimization because it used to copy
> *one-byte-at-a-time*, but our memset already knows about byte boundaries
> and tries to write more at a time when possible. i suspect you are
> seeing slower results with your implementation because of increased code
> size and branch hits. you're unlikely to see much improvement compared
> to the current version unless you either unroll the loop or do some more
> clever instruction scheduling.
> 
> the three routines in arch/parisc/lib/lusercopy.S are probably better
> targets for optimization because they are all doing one-byte-at-a-time
> operations, so there is more room for improvement.
> 
> randolph
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