It would be useful to understand how much the total time spend stalling on allocations in ZGC would be. There is currently a ZGC Allocation Stall (jdk.ZAllocationStall) duration event, that will tell you a stall took place, and the total duration of the stall. The default threshold is 10ms. This is very useful, but without something indicating the total time stalled, it is hard to know if there is quite a lot of stalls just under the threshold.

It would be useful to have a periodic/requestable (once per chunk by default) event (jdk.ZGCStallStatistics) which is simply just counting the stalls and summing up the stall time.