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Subject[PATCH 0/2] optimise blk_try_enter_queue()
Date
Kill extra rcu_read_lock/unlock() pair in blk_try_enter_queue().
Testing with io_uring (high batching) with nullblk:

Before:
3.20% io_uring [kernel.vmlinux] [k] __rcu_read_unlock
3.05% io_uring [kernel.vmlinux] [k] __rcu_read_lock

After:
2.52% io_uring [kernel.vmlinux] [k] __rcu_read_unlock
2.28% io_uring [kernel.vmlinux] [k] __rcu_read_lock

Doesn't necessarily translates into 1.4% perfofrmance improvement
but nice to have.

Pavel Begunkov (2):
percpu_ref: percpu_ref_tryget_live() version holding RCU
block: kill extra rcu lock/unlock in queue enter

block/blk-core.c | 2 +-
include/linux/percpu-refcount.h | 31 +++++++++++++++++++++----------
2 files changed, 22 insertions(+), 11 deletions(-)

--
2.33.1

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