testing/benchmark: paranoia - make sure n always grows

R=wcn
CC=golang-dev
https://golang.org/cl/223075

diff --git a/src/pkg/testing/benchmark.go b/src/pkg/testing/benchmark.go
index 6d95c90df068f046870dab560a41bab83c7b132e..6266de9323123f0eb38ddbd5cd929e57a72b20ee 100644 (file)
--- a/src/pkg/testing/benchmark.go
+++ b/src/pkg/testing/benchmark.go
@@ -78,6 +78,13 @@ func min(x, y int) int {
        return x
 }
 
+func max(x, y int) int {
+       if x < y {
+               return y
+       }
+       return x
+}
+
 // roundDown10 rounds a number down to the nearest power of 10.
 func roundDown10(n int) int {
        var tens = 0
@@ -125,7 +132,8 @@ func (b *B) run() {
                }
                // Run more iterations than we think we'll need for a second (1.5x).
                // Don't grow too fast in case we had timing errors previously.
-               n = min(int(1.5*float(n)), 100*last)
+               // Be sure to run at least one more than last time.
+               n = max(min(n+n/2, 100*last), last+1)
                // Round up to something easy to read.
                n = roundUp(n)
                b.runN(n)