Comments on: Comparing 160-bit hash values with SSE http://skitten.org/blog/2009/09/13/comparing-with-sse/ Blog for stuff that isn't food, drink or not having a car Fri, 23 Jul 2010 20:21:51 +0000 hourly 1 http://wordpress.org/?v=3.0.1 By: onitake http://skitten.org/blog/2009/09/13/comparing-with-sse/comment-page-1/#comment-1429 onitake Mon, 21 Dec 2009 22:16:20 +0000 http://skitten.org/blog/?p=37#comment-1429 thank you for the post. i was optimizing a small vector math library i wrote and had some trouble with the result of cmpeqps. what is it good for if i have to transfer a whole xmm register into memory to evaluate the result? movmskps was exactly what i was looking for. in my case, the work wasn't futile: my hand-optimized dot product runs about 10% faster than the mulss/addss version generated by gcc 4.2's tree-ssa optimizer, while my cross product routine reduces benchmark runtime by 20%. not as much as i expected, but i'm sure there's still room for improvement. i suspect there are still some unneccessary memory accesses. they hurt performance much more than the occasional serialization... thank you for the post.
i was optimizing a small vector math library i wrote and had some trouble with the result of cmpeqps. what is it good for if i have to transfer a whole xmm register into memory to evaluate the result?
movmskps was exactly what i was looking for.

in my case, the work wasn’t futile: my hand-optimized dot product runs about 10% faster than the mulss/addss version generated by gcc 4.2′s tree-ssa optimizer, while my cross product routine reduces benchmark runtime by 20%. not as much as i expected, but i’m sure there’s still room for improvement.
i suspect there are still some unneccessary memory accesses. they hurt performance much more than the occasional serialization…

]]> By: Joey http://skitten.org/blog/2009/09/13/comparing-with-sse/comment-page-1/#comment-1347 Joey Tue, 08 Dec 2009 02:44:53 +0000 http://skitten.org/blog/?p=37#comment-1347 This is funny. Then sad. I shall continue to avoid assembler. This is funny. Then sad. I shall continue to avoid assembler.

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