Re: [PATCH RFC] [X86] performance improvement for memcpy_64.S by fast string.

Pavel Machek
2009-11-12T23:04:13Z

> Ling, if you are interested, could you send a user-space test-app to
> this thread that everyone could just compile and run on various older
> boxes, to gather a performance profile of hand-coded versus string ops
> performance?
>
> ( And i think we can make a judgement based on cache-hot performance
> alone - if then the strings ops will perform comparatively better in
> cache-cold scenarios, so the cache-hot numbers would be a conservative
> estimate. )

Ugh, really? I'd expect cache-cold performance to be not helped at all
(memory bandwidth limit) and you'll get slow down from additional
i-cache misses...
Pavel

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