// by clearing garbage from previous runs.
	runtime.GC()
	b.resetRaces()
	b.N = n
	b.parallelism = 1
	b.ResetTimer()
	b.StartTimer()
	b.benchFunc(b)
	b.StopTimer()
	b.previousN = n
	b.previousDuration = b.duration
}

// run1 runs the first iteration of benchFunc. It reports whether more
// iterations of this benchmarks should be run.
func (b *B) run1() bool {
	if ctx := b.context; ctx != nil {

	sizes := []int{2, 4, 8, 64, 8192}
	benchFunc := func(b *testing.B, benchSize int) {
		data := StdEncoding.EncodeToString(make([]byte, benchSize))
		b.SetBytes(int64(len(data)))
		b.ResetTimer()
		for i := 0; i < b.N; i++ {
			StdEncoding.DecodeString(data)
		}
	}
	for _, size := range sizes {
		b.Run(fmt.Sprintf("%d", size), func(b *testing.B) {
			benchFunc(b, size)
		})
	}
}

		(indexSizes[len(indexSizes)-1]+len(benchmarkString)-1)/len(benchmarkString))
	benchFunc := func(b *testing.B, benchStr string) {
		b.SetBytes(int64(len(benchStr)))
		for i := 0; i < b.N; i++ {
			Count(benchStr, "=")
		}
	}
	for _, size := range indexSizes {
		b.Run(fmt.Sprintf("%d", size), func(b *testing.B) {
			benchFunc(b, benchStr[:size])
		})
	}

}

			// the benchtime and catch the failure result of the subbenchmark.
			root := &B{
				common: common{
					signal: make(chan bool),
					name:   "root",
					w:      buf,
				},
				benchFunc: func(b *B) { ok = b.Run("test", tc.f) }, // Use Run to catch failure.
				benchTime: durationOrCountFlag{d: 1 * time.Microsecond},
			}
			if tc.chatty {
				root.chatty = newChattyPrinter(root.w)
			}