> Rather than trying to cater to multiple assembly instruction implementations
> ourselves, have you tried taking the ideas in this earlier thread?
> https://lists.gnu.org/archive/html/qemu-devel/2015-10/msg05298.html
>
> Ideally, libc's memcmp() will already be using the most efficient assembly
> instructions without us having to reproduce the work of picking the
> instructions
> that work best.
>
Eric, thanks for you information. I didn't notice that discussion before.
I rewrite the buffer_find_nonzero_offset() with the 'bool memeqzero4_paolo
length'
then write a test program to check a large amount of zero pages, and use the
'time' to
recode the time takes by different optimization. Test result is like this:
SSE2:
------------------------------------------------------
| test 1 | test 2
----------------------------------------------------
Time(S):| 13.696 | 13.533
------------------------------------------------
AVX2:
-------------------------------------------
| test 1 | test 2
-------------------------------------------
Time (S):| 10.583 | 10.306
-------------------------------------------
memeqzero4_paolo:
---------------------------------------
| test 1 | test 2
---------------------------------------
Time (S):| 9.718 | 9.817
----------------------------------------
Paolo's implementation has the best performance. It seems that we can remove
the SSE2 related Intrinsics.
Liang
> --
> Eric Blake eblake redhat com +1-919-301-3266
> Libvirt virtualization library http://libvirt.org
