This change pulls the SEC options into a struct, which simplifies their handling
across various modules (e.g. PA needs to forward on SEC options from the
malloc_conf string, but it doesn't really need to know their names). While
we're here, make some of the fixed constants configurable, and unify naming from
the configuration options to the internals.
Currently that just means max_alloc, but we're about to add more. While we're
touching these lines anyways, tweak things to be more in line with testing.
This saves us a cache miss when lookup up the arena bin offset in a remote
arena during tcache flush. All arenas share the base offset, and so we don't
need to look it up repeatedly for each arena. Secondarily, it shaves 288 bytes
off the arena on, e.g., x86-64.
By carefully force-inlining the division constants and the operation sum count,
we can eliminate redundant operations in the arena-level dalloc function. Do
so.
This fixes an incorrect debug-mode assert:
- T1 starts an arena stats update and reads stack_head from another thread's
cache bin, when that cache bin has 1 item in it.
- T2 allocates from that cache bin. The cache_bin's stack_head now points to a
NULL pointer, since the cache bin is empty.
- T1 Re-reads the cache_bin's stack_head to perform an assertion check (since it
previously saw that the bin was empty, whatever stack_head points to should be
non-NULL).
For now, this is just a stub containing the ecaches, with no surrounding code
changed. Eventually all the core allocator bits will be moved in, in the
subsequent stack of commits.
Now that we've moved junking to a higher level of the allocation stack, we don't
care about this performance optimization (which only occurred in debug modes).
This distinguishes it from the PA mapped stat, which is now named "pa_mapped" to
avoid confusion. The (derived) arena stat includes base memory, and the PA stat
is no longer partially derived.
Qi Wang