On 02/09/2015 07:40, Amit Shah wrote: >> The buffer_find_nonzero_offset() will be called to check the zero page >> > during live migration, it's a hot function. buffer_find_nonzero_offset() >> > has already been optimized with SSE2 instructions, for platform that >> > supports AVX2, we can optimize this function with AVX2 instructions and >> > achieve about 25% performance gain. > This should be a good improvement. I recall Dave and I had a chat > about this in the past too. > > I've not yet reviewed the patchset, but I doubt anyone will have > objections. I'll review this shortly.
I think we need a better way to enable it than a configure option, however. AVX2 machines are rare, and no one would end up using it except perhaps Gentoo or other source-based distros. Perhaps something like the GCC ifunc attribute? Paolo
