A processing device monitors performance of a first thread of a first application executing on one of a plurality of processing cores of a storage system. The first thread comprises an internal scheduler controlling switching between a plurality of sub-threads of the first thread, and an external scheduler controlling release of the processing core by the first thread for use by at least a second thread of a second application different than the first application. In conjunction with monitoring the performance of the first thread in executing the first application, the processing device maintains a cumulative suspend time of the first thread over multiple suspensions of the first thread, with one or more of the multiple suspensions allowing at least the second thread of the second application to execute on the processing core, and generates performance measurements for sub-threads of the first thread using the cumulative suspend time.