[PATCH] virtio_blk: use noop elevator by default

Fernando Luis Vázquez Cao
2008-08-26T12:48:25Z

Hi Rusty,

Would it make sense to use noop by default? After all we do not know
what is behind the backend driver and the hypervisor is likely to do its
own scheduling anyway. I guess this is the reason the Xen guys took this
approach.

What do you think about the patch below?

- Fernando

---

From: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Subject: [PATCH] virtio_blk: use noop elevator by default

Using the noop elevator by default seems to be safest bet because we do
not know what is behind the backend driver and the hypervisor is likely
to do its own scheduling anyway.

Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
---

diff -urNp linux-2.6.27-rc4/drivers/block/virtio_blk.c linux-2.6.27-rc4-fixes/drivers/block/virtio_blk.c
--- linux-2.6.27-rc4/drivers/block/virtio_blk.c 2008-08-26 21:26:01.000000000 +0900
+++ linux-2.6.27-rc4-fixes/drivers/block/virtio_blk.c 2008-08-26 21:22:03.000000000 +0900
@@ -237,6 +237,8 @@ static int virtblk_probe(struct virtio_d
goto out_put_disk;
}

+ elevator_init(rq, "noop");
+
if (index < 26) {
sprintf(vblk->disk->disk_name, "vd%c", 'a' + index % 26);
} else if (index < (26 + 1) * 26) {