Messages in this thread |  | | From | Ming Lei <> | Subject | [PATCH V6 0/2] percpu_ref & block: reduce memory footprint of percpu_ref in fast path | Date | Wed, 30 Sep 2020 16:26:55 +0800 |
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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.
V6: - drop the 1st patch which adds percpu_ref_is_initialized() for MD only, since Christoph doesn't like it
V5: - fix memory leak on ref->data, only percpu_ref_exit() of patch 2 is modified.
V4: - rename percpu_ref_inited as percpu_ref_is_initialized
V3: - fix kernel oops on MD - add patch for avoiding to use percpu-refcount internal from md code - pass Red Hat CKI test which is done by Veronika Kabatova
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 | 131 ++++++++++++++++++++++-------- 4 files changed, 118 insertions(+), 63 deletions(-)
Cc: Veronika Kabatova <vkabatov@redhat.com> Cc: Sagi Grimberg <sagi@grimberg.me> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Jens Axboe <axboe@kernel.dk> Cc: Bart Van Assche <bvanassche@acm.org> -- 2.25.2
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