the .eh_frame format as part of the jitdump generated when
FLAG_perf_prof is enabled. The final goal is allowing precise unwinding
of callchains that include JITted code when profiling V8 using perf.
Unwinding information is stored in the body of code objects after the
code itself, prefixed with its length and aligned to a 8-byte boundary.
A boolean flag in the header signals its presence, resulting in zero
memory overhead when the generation of unwinding info is disabled or
no such information was attached to the code object.
A new jitdump record type (with id 4) is introduced for specifying
optional unwinding information for code load records. The EhFrameHdr
struct is also introduced, together with a constructor to initialise it
from the associated code object.
At this stage no unwinding information is written to the jitdump, but
the infrastructure for doing so is ready in place.
BUG=v8:4899
LOG=N
Review-Url: https://codereview.chromium.org/1993653003
Cr-Commit-Position: refs/heads/master@{#37296}
Define the ELF e_machine field for ARM64, enabling --perf-prof.
BUG=
Review-Url: https://codereview.chromium.org/1992263002
Cr-Commit-Position: refs/heads/master@{#36373}
This CL introduces static variables and global lock for writing to the
dump files, so that multiple web workers do not run into trouble.
Review URL: https://codereview.chromium.org/1839133002
Cr-Commit-Position: refs/heads/master@{#35123}
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}
The libdl library is already included on target builds of Android and needs
to be added to the build command line with a particular order to avoid
undefined references in other libraries. Fix this by only explicitly including
it in host builds and relying on the implicit inclusion on target builds.
Also remove the librt hack which is not longer necessary due to the AOSP build
bot having been removed.
BUG=chromium:469973
LOG=Y
Review URL: https://codereview.chromium.org/1036133005
Cr-Commit-Position: refs/heads/master@{#27535}
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
