This commit introduces a new mode for bytecode_dispatches_report.py
which reports the top sources of dispatches to a given bytecode and
the top destinations of dispatches from the same bytecode.
The bytecode name is passed with --top-dispatches-for-bytecode
(short form: -f), while the number of sources and destinations to
show is controlled with -n.
BUG=v8:4899
LOG=N
Review-Url: https://codereview.chromium.org/1979233002
Cr-Commit-Position: refs/heads/master@{#36284}
Adds a tool which enables annotation of the disassembly of bytecode handlers
based on perf output.
BUG=4899
LOG=N
Review-Url: https://codereview.chromium.org/1945673002
Cr-Commit-Position: refs/heads/master@{#36145}
In addition to top source-destination pairs,
bytecode_dispatches_report.py now prints the hottest bytecode handlers
by the number of times they are executed and dispatch to another one,
regardless of the dispatch target.
Be aware that this figure does not match the number of times a handler
is executed for those which may not or will never dispatch, e.g.
Return or Throw.
BUG=v8:4899
LOG=N
Review URL: https://codereview.chromium.org/1875263004
Cr-Commit-Position: refs/heads/master@{#35629}
Misattributed samples are strictly related to handlers, and the size
of this special group helps understand how accurate the profile is.
For these reasons, it makes more sense to always show this group.
LOG=N
BUG=v8:4899
Review URL: https://codereview.chromium.org/1895793002
Cr-Commit-Position: refs/heads/master@{#35585}
A new script is introduced, linux_perf_report.py, which reads Linux perf
data collected when running with FLAG_perf_basic_prof enabled and
produces an input file for flamegraph.pl, or a report of the hottest
bytecode handlers.
The bottom blocks of the produced flamegraph are bytecode handlers.
Special bottom blocks exist as well for compile routines, time spent
outside the interpreter and interpreter entry trampolines.
Because various Stubs and other pieces of JITted code do not maintain the
frame pointer, some sampled callchains might be incomplete even if V8 is
compiled with no_omit_framepointer=on. The script is able to detect the
most common anomaly where an entry trampoline appears in a chain, but not
on top, meaning that the frame of another bytecode handler is hidden. In
this case, the sample will be moved to a [misattributed] group to avoid
skewing the profile of unrelated handlers.
Misattributed samples and compilation routines are hidden by default.
BUG=v8:4899
LOG=N
Review URL: https://codereview.chromium.org/1783503002
Cr-Commit-Position: refs/heads/master@{#35574}
A new script, bytecode_dispatches_report.py reads the table produced
when FLAG_trace_ignition_dispatches is enabled and produces either a
report of top source-destination pairs, or a heatmap that can be
viewed interactively and saved to file.
BUG=v8:4899
LOG=N
Review URL: https://codereview.chromium.org/1869423002
Cr-Commit-Position: refs/heads/master@{#35438}
