[PATCH v5 0/4] cgroup notifications API and memory thresholds

["Kirill A. Shutemov" <kirill@shutemov.name>]

This patchset introduces eventfd-based API for notifications in cgroups and
implements memory notifications on top of it.

It uses statistics in memory controler to track memory usage.

Output of time(1) on building kernel on tmpfs:

Root cgroup before changes:
	make -j2  506.37 user 60.93s system 193% cpu 4:52.77 total
Non-root cgroup before changes:
	make -j2  507.14 user 62.66s system 193% cpu 4:54.74 total
Root cgroup after changes (0 thresholds):
	make -j2  507.13 user 62.20s system 193% cpu 4:53.55 total
Non-root cgroup after changes (0 thresholds):
	make -j2  507.70 user 64.20s system 193% cpu 4:55.70 total
Root cgroup after changes (1 thresholds, never crossed):
	make -j2  506.97 user 62.20s system 193% cpu 4:53.90 total
Non-root cgroup after changes (1 thresholds, never crossed):
	make -j2  507.55 user 64.08s system 193% cpu 4:55.63 total

Any comments?

v4 -> v5:
 - rework  __mem_cgroup_threshold() a bit;
 - drop __mem_cgroup_stat_reset_safe();
 - fixes based on comments.

v3 -> v4:
 - documentation.

v2 -> v3:
 - remove [RFC];
 - rebased to 2.6.33-rc2;
 - fixes based on comments;
 - fixed potential race on event removing;
 - use RCU-protected arrays to track trasholds.

v1 -> v2:
 - use statistics instead of res_counter to track resource usage;
 - fix bugs with locking.

v0 -> v1:
 - memsw support implemented.

Kirill A. Shutemov (4):
  cgroup: implement eventfd-based generic API for notifications
  memcg: extract mem_group_usage() from mem_cgroup_read()
  memcg: rework usage of stats by soft limit
  memcg: implement memory thresholds

 Documentation/cgroups/cgroups.txt |   20 ++
 Documentation/cgroups/memory.txt  |   19 ++-
 include/linux/cgroup.h            |   24 +++
 kernel/cgroup.c                   |  208 ++++++++++++++++++++-
 mm/memcontrol.c                   |  384 ++++++++++++++++++++++++++++++++++---
 5 files changed, 623 insertions(+), 32 deletions(-)