xen-blkfront: set queue paravirt flag

Xen's blkfront sets noop as the default I/O scheduler at initialization
time to avoid elevator overheads such as idling, but with the advent of
basic disk profiling capabilities this is not necessary anymore. We
should just tell the block layer that we are a paravirt front-end driver
and the elevator will automatically make the necessary adjustments.

Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Fernando Luis Vázquez Cao 2008-10-27 18:45:54 +09:00 committed by Jens Axboe
parent 7d116b626b
commit 66d352e1e4

View File

@ -338,18 +338,12 @@ wait:
static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
{
struct request_queue *rq;
elevator_t *old_e;
rq = blk_init_queue(do_blkif_request, &blkif_io_lock);
if (rq == NULL)
return -1;
old_e = rq->elevator;
if (IS_ERR_VALUE(elevator_init(rq, "noop")))
printk(KERN_WARNING
"blkfront: Switch elevator failed, use default\n");
else
elevator_exit(old_e);
queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
/* Hard sector size and max sectors impersonate the equiv. hardware. */
blk_queue_hardsect_size(rq, sector_size);