The # Bytes in all Heaps
is only updated when the garbage collection is executed, while the Private Bytes
is available at much faster update rate. (I'm not sure where that number comes from, internally, and how often it's updated.)
The amount of Private Bytes
increases just after 17:42:45. This amount does seem to match the value jump of # Bytes in all Heaps
at about 17:43:10. It looks like it took 20-25 seconds before any garbage collection was done and updated the # Bytes in all Heaps
counter.
It's hard to work out how memory allocations work from a few minutes worth of performance counters presented in a screenshot. ;) Keep running your test and see how your expectations work out over a longer time period.
TL;DR: The amount of managed bytes should correlate with private bytes, but the managed counter will only update during a garbage collection.
Small note from the OP: As this response says, the lagging in the memory can be fully explained by lagging GC. The fact that unmanaged memory also rises was not my question. So thanks @Simon.