Based on these comments in malloc.c:
size field is or'ed with NON_MAIN_ARENA if the chunk was obtained
from a non-main arena. This is only set immediately before handing
the chunk to the user, if necessary.
The NON_MAIN_ARENA flag is never set for unsorted chunks, so it
does not have to be taken into account in size comparisons.
When we pull a chunk off the unsorted list (or any list) we need to
make sure that flag is set properly before returning the chunk.
Use the rounded-up size for chunk_ok_for_memalign()
Do not scan the arena for reusable chunks if there's no arena.
Account for chunk overhead when determining if a chunk is a reuse
candidate.
mcheck interferes with memalign, so skip mcheck variants of
memalign tests.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
This patch adds a chunk scanning algorithm to the _int_memalign code
path that reduces heap fragmentation by reusing already aligned chunks
instead of always looking for chunks of larger sizes and splitting
them. The tcache macros are extended to allow removing a chunk from
the middle of the list.
The goal is to fix the pathological use cases where heaps grow
continuously in workloads that are heavy users of memalign.
Note that tst-memalign-2 checks for tcache operation, which
malloc-check bypasses.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
