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authorAndrew Jeffery <andrew@aj.id.au>2017-05-12 13:28:10 +0930
committerMichael Ellerman <mpe@ellerman.id.au>2017-05-30 14:59:51 +1000
commita3f952df3c6d205fe3b1e0e4848d3c3db4a28ef0 (patch)
tree4b5fe78d44151ba3f2c7ee22ca7c588867d0b3c7 /arch/powerpc/lib/copyuser_power7.S
parent09b6c1129f899c72d70b8bea36020644aa3b5a28 (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/copyuser_power7.S')
-rw-r--r--arch/powerpc/lib/copyuser_power7.S4
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