> 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
Thanks for your comments. ifunc is a good solution, I will send out the v2 soon. Liang
