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}
This adds timestamps to allow profiling with code space reuse. Also a couple of updates to reflect the changes in the JIT perf interface + a move of the perf-related stuff into separate files.
Unfortunately, the change only works with the latest patch to the perf tool from a Linux perf tool contributor (Stephane Eranian).
BUG=
R=yangguo@chromium.org
Review URL: https://codereview.chromium.org/255803003
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22098 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
