[dpdk-dev] [PATCH v6 0/3] Improve zero-length memzone allocation

[Anatoly Burakov]

This patchset does two things. First, it enables reserving
memzones of zero-length that are IOVA-contiguous. Second,
it fixes a long-standing race condition in reserving
zero-length memzones, where malloc heap is not locked between
stats collection and reservation, and will instead allocate
biggest element on the spot.

Some limitations are added, but they are a trade-off between
not having race conditions and user convenience. It would be
possible to lock all heaps during memzone reserve for zero-
length, and that would keep the old behavior, but given how
such allocation (especially when asking for IOVA-contiguous
memory) may take a long time, a design decision was made to
keep things simple, and only check other heaps if the
current one is completely busy.

Ideas on improvement are welcome.

v6:
- Rebase on top of 18.05
- Dropped malloc stats changes as no deprecation notice was
  sent, and i would like to integrate these changes in this
  release :)

v5:
- Use bound length if reserving memzone with zero length

v4:
- Fixes in memzone test
- Account for element padding
- Fix for wrong memzone size being returned
- Documentation fixes

Anatoly Burakov (3):
  malloc: add finding biggest free IOVA-contiguous element
  malloc: allow reserving biggest element
  memzone: improve zero-length memzone reserve

 lib/librte_eal/common/eal_common_memzone.c  |  70 ++-------
 lib/librte_eal/common/include/rte_memzone.h |  24 ++-
 lib/librte_eal/common/malloc_elem.c         |  79 ++++++++++
 lib/librte_eal/common/malloc_elem.h         |   6 +
 lib/librte_eal/common/malloc_heap.c         | 126 +++++++++++++++
 lib/librte_eal/common/malloc_heap.h         |   4 +
 test/test/test_memzone.c                    | 165 +++++++++++---------
 7 files changed, 343 insertions(+), 131 deletions(-)

-- 
2.17.0