[PATCH v5 0/3] blk-cgroup: Optimize blkcg_rstat_flush()

Waiman Long
2022-06-02T13:35:59Z

v5:
- Add a new patch 2 to eliminate the use of intermediate "ret"
variable in blkcg_css_alloc() to fix compilation warning reported
by kernel test robot.

v4:
- Update comment and eliminate "inline" keywords as suggested by TJ.

v3:
- Update comments in patch 2.
- Put rcu_read_lock/unlock() in blkcg_rstat_flush().
- Use READ_ONCE/WRITE_ONCE() to access lnode->next to reduce data
races.
- Get a blkg reference when putting into the lockless list and put it
back when removed.

This patch series improves blkcg_rstat_flush() performance by eliminating
unnecessary blkg enumeration and flush operations for those blkg's and
blkg_iostat_set's that haven't been updated since the last flush.

Waiman Long (3):
blk-cgroup: Correctly free percpu iostat_cpu in blkg on error exit
blk-cgroup: Return -ENOMEM directly in blkcg_css_alloc() error path
blk-cgroup: Optimize blkcg_rstat_flush()

block/blk-cgroup.c | 103 ++++++++++++++++++++++++++++++++++++++-------
block/blk-cgroup.h | 9 ++++
2 files changed, 96 insertions(+), 16 deletions(-)

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2.31.1