Jemalloc 4 purges dirty pages regularly during free() when the ratio of dirty
pages compared to active pages is higher than 1 << lg_dirty_mult. We set
lg_dirty_mult in jemalloc_config to limit RSS usage, but it also has an impact
on performance.
So instead of enforcing a high ratio to force more pages being purged, we keep
jemalloc's default ratio of 8, and force a regular purge of all dirty pages,
after cycle collection.
Keeping jemalloc's default ratio avoids cycle-collection-triggered purge to
have to go through really all dirty pages when there are a lot, in which case
the normal jemalloc purge during free() will already have kicked in. It also
takes care of everything that doesn't run the cycle collector still having
a level of purge, like plugins in the plugin-container.
At the same time, since jemalloc_purge_freed_pages does nothing with jemalloc 4,
repurpose the MEMORY_FREE_PURGED_PAGES_MS telemetry probe to track the time
spent in this cycle-collector-triggered purge.
The breakpad dependency in ThreadStackHelper is preventing us from
upgrading our in-tree copy to a newer version (bug 1069556). This patch
gets rid of that dependency. This makes native stack frames not work
for BHR, but because of the ftp.m.o decommissioning, native
symbolication was already broken and naive stack frames already don't
work, so we don't really lose anything from this patch.
Eventually we want to make ThreadStackHelper use other means of
unwinding, such as LUL for Linux
I added | #if 0 | around the code to fill the thread context, but left
the code in because I think we'll evenually want to reuse some of that
code.
This makes the order of |aDelay| and |aType| match those of the InitWith*()
functions.
I've made this change because the inconsistency tripped me up during the
development of part 4.
There are many sub-classes of nsExpirationTracker. In order to distinguish them
nicely in the logging of timer firings, it's necessary to manually name each
one. (This wouldn't be necessary if there was a way to stringify template
parameters, but there isn't.)
This is similar to the solution adopted for bug 1190985, a race in
netwerk's DebugMutexAutoLock. A relaxed atomic tells tools like TSan
that we're OK with this variable being touched from multiple threads.
That it's only set from within a locked mutex should ensure whatever
memory barriers we need are executed so all threads have a consistent
view of what value it contains.
Getting rid of another |volatile| usage in the codebase is just a bonus.
nsEventQueue's HasPending event is defined to simply:
return GetEvent(false, nullptr);
So we can substitute HasPendingEvent for this particular GetEvent call
to make the code clearer.
Its only purpose is to disable PGO. Where that was not already explicitly done,
or irrelevant (because the directory only contains python), I disabled it in
moz.build.
