powerpc: Tweak copy selection parameter in __copy_tofrom_user_power7()

[Michael Ellerman]

On Fri, 2017-05-12 at 03:58:10 UTC, Andrew Jeffery wrote:
> Experiments with the netperf benchmark indicated that the size selecting
> VMX-based copies in __copy_tofrom_user_power7() was suboptimal on POWER8.
> Measurements showed that parity was in the neighbourhood of 3328 bytes,
> rather than greater than 4096. The change gives a 1.5-2.0% improvement in
> performance for 4096-byte buffers, reducing the relative time spent in
> __copy_tofrom_user_power7() from approximately 7% to approximately 5% in
> the TCP_RR benchmark.
> 
> Signed-off-by: Andrew Jeffery <andrew at aj.id.au>
> Acked-by: Anton Blanchard <anton at samba.org>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/a3f952df3c6d205fe3b1e0e4848d3c

cheers