Hi Team,
Test Scenario:
I am using a single core Cortex R4 processor for Modem and running a moderate throughput test case with Sleep Disable.
I am capturing below 3 PMU events and CPU cycle counter for 10secs of the test scenario.
PMU Events : 0x06 (Data Read), 0x07 (Data Write), 0x43 (External Access Request)
I am capturing data like below:
1. Run the Throughput test case for 100secs.
2. After 100 secs enable the PMU events.
3. After 10secs, store the 3 PMU events.
Observation:
1. Before Step2, CPU idle Ratio is ~50%.
2. After Step2, CPU idle ratio has decreased to ~17%.
I am able to get the PMU data successfully.
P.S.: There is no change in workload between Step1 and Step2.
Query:
- We see a degradation in CPU idle of ~33% after enabling the PMU events.
1. Could you please help to explain, how PMU event enabling is causing the degradation in CPU idle, and if above decrease is normal?
2. Is the impact of PMU event capturing on CPU also related to which events we are capturing?
Thanks and Regards,
Manan Dixit