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| author | Lars Ellenberg <lars.ellenberg@linbit.com> | 2017-08-29 11:20:32 +0300 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2017-08-30 00:34:43 +0300 |
| commit | c51a0ef3747a412df4a7345d939190a99bc2a0cc (patch) | |
| tree | 04ec5f9a0db77d73a92d20b1bbc0782731e7ba99 /drivers/block/drbd/drbd_int.h | |
| parent | c529594f93ae64de2a84e7fff903ae6844664912 (diff) | |
| download | linux-c51a0ef3747a412df4a7345d939190a99bc2a0cc.tar.xz | |
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>
Diffstat (limited to 'drivers/block/drbd/drbd_int.h')
| -rw-r--r-- | drivers/block/drbd/drbd_int.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h index 819f9d0bc875..74a7d0b70e2c 100644 --- a/drivers/block/drbd/drbd_int.h +++ b/drivers/block/drbd/drbd_int.h @@ -745,6 +745,8 @@ struct drbd_connection { unsigned current_tle_writes; /* writes seen within this tl epoch */ unsigned long last_reconnect_jif; + /* empty member on older kernels without blk_start_plug() */ + struct blk_plug receiver_plug; struct drbd_thread receiver; struct drbd_thread worker; struct drbd_thread ack_receiver; @@ -1131,7 +1133,8 @@ extern void conn_send_sr_reply(struct drbd_connection *connection, enum drbd_sta extern int drbd_send_rs_deallocated(struct drbd_peer_device *, struct drbd_peer_request *); extern void drbd_backing_dev_free(struct drbd_device *device, struct drbd_backing_dev *ldev); extern void drbd_device_cleanup(struct drbd_device *device); -void drbd_print_uuids(struct drbd_device *device, const char *text); +extern void drbd_print_uuids(struct drbd_device *device, const char *text); +extern void drbd_queue_unplug(struct drbd_device *device); extern void conn_md_sync(struct drbd_connection *connection); extern void drbd_md_write(struct drbd_device *device, void *buffer); |