+Only valid if thinktime is set - control how many blocks to issue, before
+waiting \fBthinktime\fR microseconds. If not set, defaults to 1 which will
+make fio wait \fBthinktime\fR microseconds after every block. This
+effectively makes any queue depth setting redundant, since no more than 1 IO
+will be queued before we have to complete it and do our thinktime. In other
+words, this setting effectively caps the queue depth if the latter is larger.