This turns the perfcore format into more a log than it was before,
which lets us properly log process, thread and region
creation/destruction. This also makes it unnecessary to dump the
process' regions every time it is scheduled like we did before.
Incidentally this also fixes 'profile -c' because we previously ended
up incorrectly dumping the parent's region map into the profile data.
Log-based mmap support enables profiling shared libraries which
are loaded at runtime, e.g. via dlopen().
This enables profiling both the parent and child process for
programs which use execve(). Previously we'd discard the profiling
data for the old process.
The Profiler tool has been updated to not treat thread IDs as
process IDs anymore. This enables support for processes with more
than one thread. Also, there's a new widget to filter which
process should be displayed.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
This is a little bit messy, but basically if an ELF object is non-PIE,
we have to account for the executable mapping being at a hard-coded
offset and subtract that when doing symbolication.
There's probably a nicer way to solve this, I just hacked this together
so we can see "cc1plus" and friends in profiles. :^)
In multi-process profiles, the same ELF objects tend to occur many
times (everyone has libc.so for example) so we will quickly run out
of VM if we map each object once per process that uses it.
Fix this by adding a "mapped object cache" that maps the path of
an ELF object to a cached memory mapping and wrapping ELF::Image.
The perfcore file format was previously limited to a single process
since the pid/executable/regions data was top-level in the JSON.
This patch moves the process-specific data into a top-level array
named "processes" and we now add entries for each process that has
been sampled during the profile run.
This makes it possible to see samples from multiple threads when
viewing a perfcore file with Profiler. This is extremely cool! :^)
You can now view the individual samples in a profile one by one with
the new "Samples" view. The "old" main view moves into a "Call Tree"
tab (but it remains the default view.)
When you select a sample in the samples view, we show you the full
symbolicated backtrace in a separate view on the right hand side. :^)
This way you don't have to look at all the library names if you don't
want to. Since we're pretty good about namespacing our things, the
library names are slightly redundant information.
