Re: [PATCH 3/6] x86: Add support for the clwb instruction

On Tue, Nov 11, 2014 at 12:48:52PM -0700, Ross Zwisler wrote:

Essentially we need one additional byte at the beginning of the clflush so that we can flip it into a clflushopt by changing that byte into a 0x66 prefix. Two options are to either insert a 1 byte ASM_NOP1, or to add a 1 byte NOP_DS_PREFIX. Both have no functional effect with the plain clflush, but I've been told that executing a clflush + prefix should be faster than executing a clflush + NOP.

I see. :)

Thanks.