Take 3...this should address all the issues.
NBD doesn't work well with CFQ (or AS) schedulers, so let's default to something else. The two problems I have experienced with nbd and cfq are: 1) nbd hangs with cfq on RHEL 5 (2.6.18) -- this may well have been fixed There's a similar debian bug that has been filed as well: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=447638 There have been posts to nbd-general mailing list about problems with cfq and nbd also. 2) nbd performs about 10% better (the last time I tested) with deadline vs. cfq (the overhead of cfq doesn't provide much advantage to nbd [not being a real disk], and you end up going through the I/O scheduler on the nbd server anyway, so it makes sense that deadline is better with nbd) Signed-Off-By: Paul Clements <[EMAIL PROTECTED]> --- ./drivers/block/nbd.c.max_nbd_killed 2008-02-07 16:46:24.000000000 -0500 +++ ./drivers/block/nbd.c 2008-02-09 08:14:18.000000000 -0500 @@ -654,6 +654,7 @@ static int __init nbd_init(void) for (i = 0; i < nbds_max; i++) { struct gendisk *disk = alloc_disk(1); + elevator_t *old_e; if (!disk) goto out; nbd_dev[i].disk = disk; @@ -667,6 +668,11 @@ static int __init nbd_init(void) put_disk(disk); goto out; } + old_e = disk->queue->elevator; + if (elevator_init(disk->queue, "deadline") == 0 || + elevator_init(disk->queue, "noop") == 0) { + elevator_exit(old_e); + } } if (register_blkdev(NBD_MAJOR, "nbd")) {
