[PATCH 3.4 43/88] virtio_blk: Drop unused request tracking list

Greg Kroah-Hartman
2014-06-10T00:36:42Z

From: Asias He <asias@redhat.com>

commit f65ca1dc6a8c81c6bd72297d4399ec5f4c1f3a01 upstream.

Benchmark shows small performance improvement on fusion io device.

Before:
seq-read : io=1,024MB, bw=19,982KB/s, iops=39,964, runt= 52475msec
seq-write: io=1,024MB, bw=20,321KB/s, iops=40,641, runt= 51601msec
rnd-read : io=1,024MB, bw=15,404KB/s, iops=30,808, runt= 68070msec
rnd-write: io=1,024MB, bw=14,776KB/s, iops=29,552, runt= 70963msec

After:
seq-read : io=1,024MB, bw=20,343KB/s, iops=40,685, runt= 51546msec
seq-write: io=1,024MB, bw=20,803KB/s, iops=41,606, runt= 50404msec
rnd-read : io=1,024MB, bw=16,221KB/s, iops=32,442, runt= 64642msec
rnd-write: io=1,024MB, bw=15,199KB/s, iops=30,397, runt= 68991msec

Signed-off-by: Asias He <asias@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/block/virtio_blk.c | 10 ----------
1 file changed, 10 deletions(-)

--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -27,9 +27,6 @@ struct virtio_blk
/* The disk structure for the kernel. */
struct gendisk *disk;

- /* Request tracking. */
- struct list_head reqs;
-
mempool_t *pool;

/* Process context for config space updates */
@@ -53,7 +50,6 @@ struct virtio_blk

struct virtblk_req
{
- struct list_head list;
struct request *req;
struct virtio_blk_outhdr out_hdr;
struct virtio_scsi_inhdr in_hdr;
@@ -97,7 +93,6 @@ static void blk_done(struct virtqueue *v
}

__blk_end_request_all(vbr->req, error);
- list_del(&vbr->list);
mempool_free(vbr, vblk->pool);
}
/* In case queue is stopped waiting for more buffers. */
@@ -182,7 +177,6 @@ static bool do_req(struct request_queue
return false;
}

- list_add_tail(&vbr->list, &vblk->reqs);
return true;
}

@@ -435,7 +429,6 @@ static int __devinit virtblk_probe(struc
goto out_free_index;
}

- INIT_LIST_HEAD(&vblk->reqs);
vblk->vdev = vdev;
vblk->sg_elems = sg_elems;
sg_init_table(vblk->sg, vblk->sg_elems);
@@ -586,9 +579,6 @@ static void __devexit virtblk_remove(str
vblk->config_enable = false;
mutex_unlock(&vblk->config_lock);

- /* Nothing should be pending. */
- BUG_ON(!list_empty(&vblk->reqs));
-
/* Stop all the virtqueues. */
vdev->config->reset(vdev);