linux/drivers/block/drbd
Lars Ellenberg c51a0ef374 drbd: introduce drbd_recv_header_maybe_unplug
Recently, drbd_recv_header() was changed to potentially
implicitly "unplug" the backend device(s), in case there
is currently nothing to receive.

Be more explicit about it: re-introduce the original drbd_recv_header(),
and introduce a new drbd_recv_header_maybe_unplug() for use by the
receiver "main loop".

Using explicit plugging via blk_start_plug(); blk_finish_plug();
really helps the io-scheduler of the backend with merging requests.

Wrap the receiver "main loop" with such a plug.
Also catch unplug events on the Primary,
and try to propagate.

This is performance relevant.  Without this, if the receiving side does
not merge requests, number of IOPS on the peer can me significantly
higher than IOPS on the Primary, and can easily become the bottleneck.

Together, both changes should help to reduce the number of IOPS
as seen on the backend of the receiving side, by increasing
the chance of merging mergable requests, without trading latency
for more throughput.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-08-29 15:34:43 -06:00
..
drbd_actlog.c block: replace bi_bdev with a gendisk pointer and partitions index 2017-08-23 12:49:55 -06:00
drbd_bitmap.c block: replace bi_bdev with a gendisk pointer and partitions index 2017-08-23 12:49:55 -06:00
drbd_debugfs.c drbd: make intelligent use of blkdev_issue_zeroout 2017-04-08 11:25:38 -06:00
drbd_debugfs.h
drbd_int.h drbd: introduce drbd_recv_header_maybe_unplug 2017-08-29 15:34:43 -06:00
drbd_interval.c
drbd_interval.h drbd: code cleanups without semantic changes 2016-06-13 21:43:07 -06:00
drbd_main.c drbd: introduce drbd_recv_header_maybe_unplug 2017-08-29 15:34:43 -06:00
drbd_nl.c drbd: Drop unnecessary static 2017-06-27 17:56:50 -06:00
drbd_nla.c netlink: pass extended ACK struct to parsing functions 2017-04-13 13:58:22 -04:00
drbd_nla.h
drbd_proc.c block: Use pointer to backing_dev_info from request_queue 2017-02-02 08:20:48 -07:00
drbd_protocol.h drbd: introduce WRITE_SAME support 2016-06-13 21:43:07 -06:00
drbd_receiver.c drbd: introduce drbd_recv_header_maybe_unplug 2017-08-29 15:34:43 -06:00
drbd_req.c drbd: introduce drbd_recv_header_maybe_unplug 2017-08-29 15:34:43 -06:00
drbd_req.h drbd: introduce drbd_recv_header_maybe_unplug 2017-08-29 15:34:43 -06:00
drbd_state_change.h drbd: Backport the "events2" command 2015-11-25 09:22:00 -07:00
drbd_state.c drbd: get rid of empty statement in is_valid_state 2016-06-13 21:43:07 -06:00
drbd_state.h drbd: code cleanups without semantic changes 2016-06-13 21:43:07 -06:00
drbd_strings.c drbd: code cleanups without semantic changes 2016-06-13 21:43:07 -06:00
drbd_strings.h
drbd_vli.h
drbd_worker.c drbd: introduce drbd_recv_header_maybe_unplug 2017-08-29 15:34:43 -06:00
Kconfig
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