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. 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 | 43 +++++++++---- lib/percpu-refcount.c | 101 ++++++++++++++++++++---------- 4 files changed, 101 insertions(+), 48 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
