[PATCH V2 0/2] Reduce reclaim from per-zone LRU in global kswapd

[Ying Han <yinghan@google.com>]

The global kswapd scans per-zone LRU and reclaims pages regardless of the
cgroup. It breaks memory isolation since one cgroup can end up reclaiming
pages from another cgroup. Instead we should rely on memcg-aware target
reclaim including per-memcg kswapd and soft_limit hierarchical reclaim under
memory pressure.

In the global background reclaim, we do soft reclaim before scanning the
per-zone LRU. However, the return value is ignored. This patch is the first
step to skip shrink_zone() if soft_limit reclaim does enough work.

This is part of the effort which tries to reduce reclaiming pages in global
LRU in memcg. The per-memcg background reclaim patchset further enhances the
per-cgroup targetting reclaim, which I should have V4 posted shortly.

Try running multiple memory intensive workloads within seperate memcgs. Watch
the counters of soft_steal in memory.stat.

$ egrep 'steal|scan' /dev/cgroup/1/memory.stat
soft_steal 259200
total_soft_steal 259200

Ying Han (2):
  count the soft_limit reclaim in global background reclaim
  add stats to monitor soft_limit reclaim

 Documentation/cgroups/memory.txt |    2 +
 include/linux/memcontrol.h       |   11 ++++++++-
 include/linux/swap.h             |    3 +-
 mm/memcontrol.c                  |   43 ++++++++++++++++++++++++++++++--------
 mm/vmscan.c                      |   16 +++++++++++--
 5 files changed, 60 insertions(+), 15 deletions(-)

-- 
1.7.3.1

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