This makes sure that profiler threads are properly included in sample data on
Linux. This was previously working because sample capture was performed
system-wide. Now samples are only captured in client context, which includes
all spawned threads. Since this inclusion only works for threads which will be
spawned after the trace starts, no thread can be created before sampling setup
is done.
The C++11 spec states in [basic.stc.thread] thread storage duration:
2. A variable with thread storage duration shall be initialized before its
first odr-use (3.2) and, if constructed, shall be destroyed on thread exit.
Previously Tracy relied on the TLS data being initialized:
- During thread creation (MSVC).
- Or during first use in a thread, but the initialization was performed for
the whole TLS block.
It seems that new compilers are more granular with how they perform the
initialization, hence rpmalloc init has to be checked before each allocation,
as it cannot be "folded" into, for example, initialization of the profiler
itself.
Fuck knows how this is supposed to work. perf_event_open() opens the
descriptor successfully, but it produces no samples, if precise_ip is not 0.
There are no such problems on ARM (where precise_ip is 3, but maybe it is not
supported at all on that architecture, again, fuck knows if), and on AMD
perf_event_open() does not succeed when precise_ip > 0.
Original commit a6b25497 by xavier <xavierb@gmail.com>:
add TRACY_CALLSTACK_IGNORE_INLINES to tradeoff speed vs precision in win32 DecodeCallstackPtr()
SymQueryInlineTrace() is too slow in some cases:
300000 queries backlog getting processed at ~70 per second is prohibitive.
(without inlines resolution, it's more like ~20000 queries per second)
Bartosz Taudul
Bartosz Taudul