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jarin authored
Difference from --perf-basic-prof: - correctly attributes samples when code space gets reused (when unused code object dies and a new code objects is allocated at the same place). - outputs compiled machine code for instruction-level profile. Just like --perf-basic-prof, the file writer is not synchronized (even worse, there is a per-isolate file handle), so we will run into trouble with multiple isolates. However, this patch is still an improvement on --perf-basic-prof, and it should be fine to replace ll-prof. The patch also introduces experimental support for debug info, but it does not seem to be picked by the perf tool. Usage: You need the perf tool from Linux kernel >4.5. Then run: $ perf record -k mono d8 --perf-prof <your JS file> $ perf inject -j -i perf.data -o perf.data.jitted $ perf report -i perf.data.jitted Some explanations: The "-k mono" switch from "perf record" tells the perf tool to use the monotonic clock for perf sample timestamping. The "perf inject -j" command injects the collected code events into the perf data file, writing the output into perf.data.jitted. The perf report command then creates the report. Review URL: https://codereview.chromium.org/1809203007 Cr-Commit-Position: refs/heads/master@{#35091}
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