diff options
| author | Andrew Jeffery <andrew@aj.id.au> | 2017-05-12 13:28:10 +0930 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2017-05-30 14:59:51 +1000 |
| commit | a3f952df3c6d205fe3b1e0e4848d3c3db4a28ef0 (patch) | |
| tree | 4b5fe78d44151ba3f2c7ee22ca7c588867d0b3c7 /arch/powerpc/lib | |
| parent | 09b6c1129f899c72d70b8bea36020644aa3b5a28 (diff) | |
powerpc: Tweak copy selection parameter in __copy_tofrom_user_power7()
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@aj.id.au>
Acked-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/lib')
| -rw-r--r-- | arch/powerpc/lib/copyuser_power7.S | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/powerpc/lib/copyuser_power7.S b/arch/powerpc/lib/copyuser_power7.S index a24b4039352c..706b7cc19846 100644 --- a/arch/powerpc/lib/copyuser_power7.S +++ b/arch/powerpc/lib/copyuser_power7.S @@ -82,14 +82,14 @@ _GLOBAL(__copy_tofrom_user_power7) #ifdef CONFIG_ALTIVEC cmpldi r5,16 - cmpldi cr1,r5,4096 + cmpldi cr1,r5,3328 std r3,-STACKFRAMESIZE+STK_REG(R31)(r1) std r4,-STACKFRAMESIZE+STK_REG(R30)(r1) std r5,-STACKFRAMESIZE+STK_REG(R29)(r1) blt .Lshort_copy - bgt cr1,.Lvmx_copy + bge cr1,.Lvmx_copy #else cmpldi r5,16 |