Hi,
The 1st patch removes memory footprint of percpu_ref in fast path
from 7 words to 2 words, since it is often used in fast path and
embedded in user struct.
The 2nd patch moves .q_usage_counter to 1st cacheline of
'request_queue'.
Simple test on null_blk shows ~2% IOPS boost on one 16cores(two threads
per core) machine, dual socket/numa.
V2:
- pass 'gfp' to kzalloc() for fixing block/027 failure reported by
kernel test robot
- protect percpu_ref_is_zero() with destroying percpu-refcount by
spin lock
Ming Lei (2):
percpu_ref: reduce memory footprint of percpu_ref in fast path
block: move 'q_usage_counter' into front of 'request_queue'
drivers/infiniband/sw/rdmavt/mr.c | 2 +-
include/linux/blkdev.h | 3 +-
include/linux/percpu-refcount.h | 45 ++++-------
lib/percpu-refcount.c | 128 ++++++++++++++++++++++--------
4 files changed, 115 insertions(+), 63 deletions(-)
Cc: Sagi Grimberg <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Bart Van Assche <[email protected]>
--
2.25.2
