> 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