Commit 078be02b authored by Michal Belczyk's avatar Michal Belczyk Committed by Linus Torvalds
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nbd: increase default and max request sizes 



Raise the default max request size for nbd to 128KB (from 127KB) to get it
4KB aligned.  This patch also allows the max request size to be increased
(via /sys/block/nbd<x>/queue/max_sectors_kb) to 32MB.

The patch makes nbd network traffic more efficient by:
- reducing request fragmentation (4KB alignment)
- reducing the number of requests (fewer round trips, less network overhead)

Especially in high latency networks, larger request size can make a dramatic

Signed-off-by: default avatarPaul Clements <paul.clements@steeleye.com>
Signed-off-by: default avatarMichal Belczyk <belczyk@bsd.krakow.pl>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5cc54451

drivers/block/nbd.c

+2 −0
Original line number Diff line number Diff line
@@ -856,6 +856,8 @@ static int __init nbd_init(void) 
		disk->queue->limits.discard_granularity = 512;

		disk->queue->limits.max_discard_sectors = UINT_MAX;

		disk->queue->limits.discard_zeroes_data = 0;

		blk_queue_max_hw_sectors(disk->queue, 65536);

		disk->queue->limits.max_sectors = 256;

	}



	if (register_blkdev(NBD_MAJOR, "nbd")) {