const runtime.timeHistSubBucketBits

5 uses

	runtime (current package)
		histogram.go#L67: 	timeHistSubBucketBits = 2
		histogram.go#L68: 	timeHistNumSubBuckets = 1 << timeHistSubBucketBits
		histogram.go#L133: 	subBucket := uint(duration>>(bucketBit-1-timeHistSubBucketBits)) % timeHistNumSubBuckets
		histogram.go#L176: 		bucketNanos := uint64(j) << (timeHistMinBucketBits - 1 - timeHistSubBucketBits)
		histogram.go#L188: 			bucketNanos |= uint64(j) << (i - 1 - timeHistSubBucketBits)