Re: powerpc: During context switch, check before setting mm_cpumask

On Mon, 2016-03-10 at 06:40:29 UTC, Anton Blanchard wrote:

From: Anton Blanchard <redacted>

During context switch, switch_mm() sets our current CPU in mm_cpumask.
We can avoid this atomic sequence in most cases by checking before
setting the bit.

Testing on a POWER8 using our context switch microbenchmark:

tools/testing/selftests/powerpc/benchmarks/context_switch \
	--process --no-fp --no-altivec --no-vector

Performance improves 2%.

Signed-off-by: Anton Blanchard <redacted>
Acked-by: Balbir Singh <bsingharora@gmail.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/bb85fb5803270c52863b983596c2a0

cheers