Re: [PATCH] x86-64: espfix for 64-bit mode *PROTOTYPE*

Andrew Lutomirski
2014-04-22T01:06:44Z

On Mon, Apr 21, 2014 at 5:53 PM, H. Peter Anvin <hpa@zytor.com> wrote:
> Well, if 2^17 CPUs are allocated we might 2K pages allocated. We could easily do a bitmap here, of course. NR_CPUS/64 is a small number, and would reduce the code complexity.
>

Even simpler: just get rid of the check entirely. That is, break out
of the higher level loops once one of them is set (this should be a
big speedup regardless) and don't allocate the page if the first PTE
is already pointing at something.

After all, espfix_already_there is mostly a duplicate of init_espfix_cpu.

--Andy