Re: Built a neon version copy_page/clear_page is correct?

Yes. I have a bottleneck, maybe it’s not copy_page’s. but
during the debugging process, this function has a very high
CPU utilization. 

The test program is UnixBench’s src/spawn.c, with a while to 
fork process. The only variable for test is PAGE_SIZE, one is
4k PAGE_SIZE, next is 64k PAGE_SIZE.

result for "perf top":
4k  |  13% CPU  copy_page 
64k |  48% CPU  copy_page

This is why I want to optimize this function. Maybe bottleneck
is not here?

在 2018年12月12日，15:18，Ard Biesheuvel [off-list ref] 写道：

As for copy_page(), please describe a use case where it is a
bottleneck, and reason about how much you could improve performance in
that case by improving the speed of copy_page() itself. Otherwise,
we're just adding NEON routines for the sake if it, which is a bad
idea imo.

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