[PATCH -next v4 00/17] rbtree: cache leftmost node internally

[Davidlohr Bueso <dave@stgolabs.net>]

Changes from v3 (https://lwn.net/Articles/726809/):
- Updated Documentation/rbtree.txt in patch 1.
- Explicitly mentioned the asymmetry wrt rightmost node in patch 1 (hch).
- Most changes in the set is adding more patches: patch 2,3,4,5,6,15,16,17.
- Added Peter's ack.

Changes from v2 (https://lkml.org/lkml/2017/6/8/857):
- Fixed 0day reported crash for drm_mm selftest program. We were
not correctly using the cached version of rbtree with the allocated
nodes.
- Added cfq patch to use internal rbtree caching.
- Added Christian's and Jan's reviews.

Changes from v1 (https://marc.info/?l=linux-kernel&m=149611025616685):
- No longer rfc.
- Removed bogus semimcolon in rb_first_cached()
- Updated missing interval tree user drivers/infiniband/hw/hfi1/
- Removed redundant @cached arg in when erasing a node.
- Added more patches that make use of rb_first_cached(), which I
  thought might be worth it: procfs and epoll.
- Cc more people for patch 5, which touches drivers such as infiniband
and gpu. The rest of the changes are pretty covered with the current
Cc'ed maintainers and mm folks.

Hi,

Here's a proposal for extending rbtrees to internally cache the leftmost
node such that we can have fast overlap check optimization for all interval
tree users[1]. The benefits of this series are that:

(i)   Unify users that do internal leftmost node caching.
(ii)  Optimize all interval tree users.
(iii) Convert at least two new users (epoll and procfs) to the new interface.
(iv)  Enable user rightmost node caching, similar to how we deal with the
      leftmost case before this patchset.

Patch 1: Layout the rb machinery.

Patch 2,3: Adds an unlikely() prediction to root-most node for insertions
as well as some minor comment enhancements.

Patches 4-6: Improve and extend rbrtee_test.c program.

Patches 7-10:  Make use of the internal leftmost node in scheduler, realtime
mutexes and cfq.

Patch 11: Implements fast overlap checks for interval trees.

Patch 12: rocket science.

Patches 13-15: Patches that convert to O(1) rb_first_cached().

Patches 16,17: Apply rightmost node optimization explicitly by two users.

The series has survived booting, kernel builds and pistress workloads.

Applies on top of today's -next.

Thanks!

Davidlohr Bueso (17):
  rbtree: cache leftmost node internally
  rbtree: optimize root-check during rebalancing loop
  rbtree: add some additional comments for rebalancing cases
  lib/rbtree_test.c: make input module parameters
  lib/rbtree_test.c: add (inorder) traversal test
  lib/rbtree_test.c: support rb_root_cached
  sched/fair: replace cfs_rq->rb_leftmost
  sched/deadline: replace earliest dl and rq leftmost caching
  locking/rtmutex: replace top-waiter and pi_waiters leftmost caching
  block/cfq: replace cfq_rb_root leftmost caching
  lib/interval_tree: fast overlap detection
  lib/interval-tree: correct comment wrt generic flavor
  procfs: use faster rb_first_cached()
  fs/epoll: use faster rb_first_cached()
  fs/ext4: use cached rbtrees
  mem/memcg: cache rightmost node
  block/cfq: cache rightmost rb_node

 Documentation/rbtree.txt                           |  33 +++
 block/cfq-iosched.c                                |  81 +++-----
 drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c             |   8 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c             |   7 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h             |   2 +-
 drivers/gpu/drm/drm_mm.c                           |  19 +-
 drivers/gpu/drm/drm_vma_manager.c                  |   2 +-
 drivers/gpu/drm/i915/i915_gem_userptr.c            |   6 +-
 drivers/gpu/drm/radeon/radeon.h                    |   2 +-
 drivers/gpu/drm/radeon/radeon_mn.c                 |   8 +-
 drivers/gpu/drm/radeon/radeon_vm.c                 |   7 +-
 drivers/infiniband/core/umem_rbtree.c              |   4 +-
 drivers/infiniband/core/uverbs_cmd.c               |   2 +-
 drivers/infiniband/hw/hfi1/mmu_rb.c                |  10 +-
 drivers/infiniband/hw/usnic/usnic_uiom.c           |   6 +-
 drivers/infiniband/hw/usnic/usnic_uiom.h           |   2 +-
 .../infiniband/hw/usnic/usnic_uiom_interval_tree.c |  15 +-
 .../infiniband/hw/usnic/usnic_uiom_interval_tree.h |  12 +-
 drivers/vhost/vhost.c                              |   2 +-
 drivers/vhost/vhost.h                              |   2 +-
 fs/eventpoll.c                                     |  30 +--
 fs/ext4/dir.c                                      |  24 ++-
 fs/ext4/ext4.h                                     |   4 +-
 fs/ext4/mballoc.c                                  |  22 +-
 fs/hugetlbfs/inode.c                               |   6 +-
 fs/inode.c                                         |   2 +-
 fs/proc/generic.c                                  |  26 +--
 fs/proc/internal.h                                 |   2 +-
 fs/proc/proc_net.c                                 |   2 +-
 fs/proc/root.c                                     |   2 +-
 include/drm/drm_mm.h                               |   2 +-
 include/linux/fs.h                                 |   4 +-
 include/linux/init_task.h                          |   5 +-
 include/linux/interval_tree.h                      |   8 +-
 include/linux/interval_tree_generic.h              |  48 ++++-
 include/linux/mm.h                                 |  17 +-
 include/linux/rbtree.h                             |  21 ++
 include/linux/rbtree_augmented.h                   |  33 ++-
 include/linux/rmap.h                               |   4 +-
 include/linux/rtmutex.h                            |  11 +-
 include/linux/sched.h                              |   3 +-
 include/rdma/ib_umem_odp.h                         |  11 +-
 include/rdma/ib_verbs.h                            |   2 +-
 kernel/fork.c                                      |   3 +-
 kernel/locking/rtmutex-debug.c                     |   2 +-
 kernel/locking/rtmutex.c                           |  35 +---
 kernel/locking/rtmutex_common.h                    |  12 +-
 kernel/sched/deadline.c                            |  50 ++---
 kernel/sched/debug.c                               |   2 +-
 kernel/sched/fair.c                                |  39 ++--
 kernel/sched/sched.h                               |   9 +-
 lib/interval_tree_test.c                           |   4 +-
 lib/rbtree.c                                       |  65 ++++--
 lib/rbtree_test.c                                  | 230 +++++++++++++++++----
 mm/interval_tree.c                                 |  10 +-
 mm/memcontrol.c                                    |  23 ++-
 mm/memory.c                                        |   4 +-
 mm/mmap.c                                          |  10 +-
 mm/rmap.c                                          |   4 +-
 59 files changed, 643 insertions(+), 378 deletions(-)

-- 
2.12.0