This pulls out the various abstractions where some stats counter is sometimes an
atomic, sometimes a plain variable, sometimes always protected by a lock,
sometimes protected by reads but not writes, etc. With this change, these cases
are treated consistently, and access patterns tagged.
In the process, we fix a few missed-update bugs (where one caller assumes
"protected-by-a-lock" semantics and another does not).
This is logically at a higher level of the stack; extent should just allocate
things at the page-level; it shouldn't care exactly why the callers wants a
given number of pages.
Previously, large allocations in tcaches would have their sizes reduced during
stats estimation. Added a test, which fails before this change but passes now.
This fixes a bug introduced in 5934846612, which
was itself fixing a bug introduced in 9c0549007d.
Previously, we took an array of cache_bin_info_ts and an index, and dereferenced
ourselves. But infos for other cache_bins aren't relevant to any particular
cache bin, so that should be the caller's job.
This is debug only and we keep it off the fast path. Moving it here simplifies
the internal logic.
This never tries to junk on regions that were shrunk via xallocx. I think this
is fine for two reasons:
- The shrunk-with-xallocx case is rare.
- We don't always do that anyway before this diff (it depends on the opt
settings and extent hooks in effect).
Previously, tcache fill/flush (as well as small alloc/dalloc on the arena) may
potentially drop the bin lock for slab_alloc and slab_dalloc. This commit
refactors the logic so that the slab calls happen in the same function / level
as the bin lock / unlock. The main purpose is to be able to use flat combining
without having to keep track of stack state.
In the meantime, this change reduces the locking, especially for slab_dalloc
calls, where nothing happens after the call.
What we call an arena_ind is really the index associated with some particular
set of ehooks; the arena is just the user-visible portion of that. Making this
explicit, and reframing checks in terms of that, makes the code simpler and
cleaner, and helps us avoid passing the arena itself all throughout extent code.
This lets us put back an arena-specific assert.
Previously, it was really more like extents_alloc (it looks in an ecache for an
extent to reuse as its primary allocation pathway). Make that pathway more
explciitly like extents_alloc, and rename extent_alloc_wrapper_hard accordingly.
This will eventually completely wrap the eset, and handle concurrency,
allocation, and deallocation. For now, we only pull out the mutex from the
eset.
If there are custom extent hooks, pages_can_purge_lazy is not necessarily the
right guard. We could check ehooks_are_default too, but the case where
purge_lazy is unsupported is rare and getting rarer. Just checking the decay
interval captures most of the benefit.
When deferred initialization was added, initializing required copying
sizeof(extent_hooks_t) bytes after a pointer chase. Today, it's just a single
pointer loaded from the base_t. In subsequent diffs, we'll get rid of even that.
