HMaster currently shows Requests Per Second per RegionServer under HMaster UI's /master-status page -> Region Servers -> Base Stats section in the Web UI.
Please add Reads Per Second and Writes Per Second per RegionServer alongside this in the HMaster UI, and also expose the Read/Write/Total requests per sec information in the HMaster JMX API.
This will make it easier to find read or write hotspotting on HBase as a combined total will minimize and mask differences between RegionServers. For example, we do 30,000 reads/sec but only 900 writes/sec to each RegionServer, so write skew will be masked as it won't show enough significant difference in the much larger combined Total Requests Per Second stat.
For now I've written a Python tool to calculate this info from RegionServers JMX read/write/total request counts but since HMaster is collecting this info anyway it shouldn't be a big change to improve it to also show Reads / Writes Per Sec as well as Total.
Find my tools for more granular Read/Write Requests Per Sec Per Regionserver and also Per Region at my PyTools github repo along with a selection of other HBase tools I've used for performance debugging over the years.