From 078be02b80359a541928c899c2631f39628f56df Mon Sep 17 00:00:00 2001 From: Michal Belczyk Date: Tue, 30 Apr 2013 15:28:28 -0700 Subject: [PATCH] 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/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: Paul Clements Signed-off-by: Michal Belczyk Cc: Jens Axboe Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/block/nbd.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 7fecc78..037288e 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -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")) { -- 2.7.4