runtime: warn that cputicks() might not be monotonic.
Get rid of gocputicks(), it is no longer used.
LGTM=bradfitz, dave
R=golang-codereviews, bradfitz, dave, minux
CC=golang-codereviews
https://golang.org/cl/161110044
diff --git a/src/runtime/stubs.go b/src/runtime/stubs.go
index 6561094..3419047 100644
--- a/src/runtime/stubs.go
+++ b/src/runtime/stubs.go
@@ -180,7 +180,11 @@
func breakpoint()
func nanotime() int64
func usleep(usec uint32)
+
+// careful: cputicks is not guaranteed to be monotonic! In particular, we have
+// noticed drift between cpus on certain os/arch combinations. See issue 8976.
func cputicks() int64
+
func mmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off uint32) unsafe.Pointer
func munmap(addr unsafe.Pointer, n uintptr)
func madvise(addr unsafe.Pointer, n uintptr, flags int32)
