Re: [PATCH] MIPS: Define __arch_swab64 for all mips r2 cpus (v2).

[Ralf Baechle <ralf@linux-mips.org>]

On Tue, Jun 30, 2009 at 06:13:41PM -0700, David Daney wrote:

> The problem with CPU_MIPS64_R2 in the kernel is that it means two  
> unrelated things:
>
> 1) The cpu can execute all mips64r2 ISA instructions.
>
> 2) The cpu requires that all worse case cache and execution hazards are  
> handled.
>
> In the case of the Octeon processors, #1 is true, but we can get better  
> performance by omitting many of the hazard barriers because they are  
> unneeded.

The most performance sensitive hazard barriers are the ones in the TLB
exception handlers and they're now being handled in C code in tlbex.c
which mostly does runtime decissions.  I suspect the remaining hazard
barriers are not a big performance thing anymore.

  Ralf