6.11. Cycle-accurate tracing

When profiling the execution of critical code sequences, it is often useful if you can observe the exact number of cycles that a particular code sequence takes to execute. To perform this cycle-accurate tracing, you must set bit [12] of the ETMCR to 1, see Main Control Register, ETMCR.

When cycle-accurate tracing is enabled, TRACEPKT[0] is HIGH when PIPESTAT has the value 0x7 (TD). This causes the TCD to capture trace on all cycles, even if there is no trace to output on that cycle. The number of cycles taken by a region of code can therefore be determined by counting the number of cycles of trace captured.

Cycle-accurate tracing is disabled when:

Copyright © 1999-2002, 2004-2009, 2011 ARM Limited. All rights reserved.ARM IHI 0014Q
Non-ConfidentialID101211