runtime: eliminate false sharing during stack growth
Remove static variable from runtime·oldstack().
Benchmark results on HP Z600 (2 x Xeon E5620, 8 HT cores, 2.40GHz)
are as follows (with CL
4657091 applied):
benchmark old ns/op new ns/op delta
BenchmarkStackGrowth 1183.00 1180.00 -0.25%
BenchmarkStackGrowth-2 1249.00 1211.00 -3.04%
BenchmarkStackGrowth-4 954.00 805.00 -15.62%
BenchmarkStackGrowth-8 701.00 683.00 -2.57%
BenchmarkStackGrowth-16 465.00 415.00 -10.75%
R=rsc
CC=golang-dev
https://golang.org/cl/
4693042