2.4. Timestamping

The PFT architecture supports timestamping. This is a mechanism where a time value is inserted into the trace stream periodically. The PTM inserts additional timestamps in the trace stream at points where you are likely to find them useful. A system that implements timestamping must include a counter to provide the source of the timestamp values, and must broadcast the same value to all compatible trace sources in the system. Each trace source samples the timestamp value and inserts it as an absolute value in the trace stream.

This timestamping mechanism provides the following features:

The PTM inserts timestamps in the trace stream with optional cycle accuracy. It also inserts timestamps:

This enables close temporal correlation of code around spinlocks and other inter-processor communications.

Note

Bit [25] of the ETMCCER determines whether the PTM inserts timestamps for DMB and DSB operations, see Configuration Code Extension Register, ETMCCER.

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