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SubjectRE: [PATCH RFC 2/2] [x86] Optimize copy_page by re-arranging instruction sequence and saving register
Date
> If you can't test the CPUs who run this code I think it's safer if you
> add a new variant for Atom, not change the existing well tested code.
> Otherwise you risk performance regressions on these older CPUs.

I found one older machine, and tested the code on it, the results between them are almost the same as below(attached cpu info).
1 copy_page_org copy_page_new
2 TPT: Len 4096, alignment 0/ 0: 2252 2218
3 TPT: Len 4096, alignment 0/ 0: 2244 2193
4 TPT: Len 4096, alignment 0/ 0: 2261 2227
5 TPT: Len 4096, alignment 0/ 0: 2235 2244
6 TPT: Len 4096, alignment 0/ 0: 2261 2184

Thanks
Ling
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