We have noticed several regressions in read/write balance with execution control turned on. For example, in a workload with 25% reads and 75% writes, we observe that write throughput increases at the expense of read throughput since read and write tickets share the same pool. We indirectly end up tuning the number of read tickets based on available write tickets.
 
We should add a server parameter to control the ratio of of read/write tickets. We should also test the performance impact by running existing mixed_workloads_genny with a 75/25 read/write ratio.