Here are some ways for reducing and handling the massive amount of trace data: perf tools do not support output of Intel PT to Intel® Trace Hub. CPU overhead is low, but memory bandwidth consumption can be significant. Perf tools support output to memory buffers.
That can be at a faster rate than it can be recorded to file (resulting in trace data loss), and sometimes faster even than can be recording to memory (resulting in overflow packets). Intel PT can potentially produce hundreds of megabytes of trace data per CPU per second. Reducing and handling the massive amount of trace data Instead of taking a test case and creating a trace of it, you need first to create a test case that is suitable for tracing. That inverts the way performance analysis is normally done. Such an enormous amount of trace data creates a number of challenges, but it raises the central question: how to reduce the amount of trace data that needs to be captured. It provides fine-grained information on branches taken in a program, but that means there can be a vast amount of trace data. Intel PT essentially provides control flow tracing, and you can get all the technical details in the Intel Processor Trace chapter in the Intel SDM ( ).Ĭontrol flow tracing is different from other kinds of performance analysis and debugging. Intel processors (Broadwell or newer, or Apollo Lake or newer) have a performance analysis and debugging feature called Intel® Processor Trace, or Intel® PT for short. Introduction What is Intel® Processor Trace 17 Appendix: Intel PT capabilities on different processors.15 Example: Using PTWRITE to measure the time of an individual instruction.13 Example: Detecting System Management Mode (SMM).10 Example: Looking at Intel PT trace packets.9 Example: Using SQL to analyze latencies.5 Example: Tracing power events and CPU frequency.4 Example: Tracing short-running commands.3 Example: Tracing your own code : Hello World.2.1 Downloading and building the latest perf tools.1.1.3.2 Intel® Transactional Synchronization Extensions (Intel® TSX).1.1.2.4 Intel PT vs Branch Trace Store (BTS).
1.1.2.3 Intel PT vs Last Branch Record (LBR).1.1.2.1 Intel PT vs Performance Counters.
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