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virtio-blk: Use bdrv_aio_multiwrite 

It is quite common for virtio-blk to submit more than one write request in a
row to the qemu block layer. Use bdrv_aio_multiwrite to allow block drivers to
optimize its handling of the requests.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Kevin Wolf 2009-09-09 17:53:38 +02:00 committed by Anthony Liguori
parent 40b4f53967
commit 91553dcc9e
1 changed files with 42 additions and 8 deletions
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50
hw/virtio-blk.c
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@ -252,17 +252,42 @@ static void virtio_blk_handle_scsi(VirtIOBlockReq *req)
}
#endif /* __linux__ */
static void virtio_blk_handle_write(VirtIOBlockReq *req)
static void do_multiwrite(BlockDriverState *bs, BlockRequest *blkreq,
int num_writes)
{
BlockDriverAIOCB *acb;
int i, ret;
ret = bdrv_aio_multiwrite(bs, blkreq, num_writes);
acb = bdrv_aio_writev(req->dev->bs, req->out->sector, &req->qiov,
req->qiov.size / 512, virtio_blk_rw_complete, req);
if (!acb) {
virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
if (ret != 0) {
for (i = 0; i < num_writes; i++) {
if (blkreq[i].error) {
virtio_blk_req_complete(blkreq[i].opaque, VIRTIO_BLK_S_IOERR);
}
}
}
}
static void virtio_blk_handle_write(BlockRequest *blkreq, int *num_writes,
VirtIOBlockReq *req, BlockDriverState **old_bs)
{
if (req->dev->bs != *old_bs || *num_writes == 32) {
if (*old_bs != NULL) {
do_multiwrite(*old_bs, blkreq, *num_writes);
}
*num_writes = 0;
*old_bs = req->dev->bs;
}
blkreq[*num_writes].sector = req->out->sector;
blkreq[*num_writes].nb_sectors = req->qiov.size / 512;
blkreq[*num_writes].qiov = &req->qiov;
blkreq[*num_writes].cb = virtio_blk_rw_complete;
blkreq[*num_writes].opaque = req;
blkreq[*num_writes].error = 0;
(*num_writes)++;
}
static void virtio_blk_handle_read(VirtIOBlockReq *req)
{
BlockDriverAIOCB *acb;
@ -278,6 +303,9 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
{
VirtIOBlock *s = to_virtio_blk(vdev);
VirtIOBlockReq *req;
BlockRequest blkreq[32];
int num_writes = 0;
BlockDriverState *old_bs = NULL;
while ((req = virtio_blk_get_request(s))) {
if (req->elem.out_num < 1 || req->elem.in_num < 1) {
@ -299,13 +327,18 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
} else if (req->out->type & VIRTIO_BLK_T_OUT) {
qemu_iovec_init_external(&req->qiov, &req->elem.out_sg[1],
req->elem.out_num - 1);
virtio_blk_handle_write(req);
virtio_blk_handle_write(blkreq, &num_writes, req, &old_bs);
} else {
qemu_iovec_init_external(&req->qiov, &req->elem.in_sg[0],
req->elem.in_num - 1);
virtio_blk_handle_read(req);
}
}
if (num_writes > 0) {
do_multiwrite(old_bs, blkreq, num_writes);
}
/*
* FIXME: Want to check for completions before returning to guest mode,
* so cached reads and writes are reported as quickly as possible. But
@ -324,7 +357,8 @@ static void virtio_blk_dma_restart_bh(void *opaque)
s->rq = NULL;
while (req) {
virtio_blk_handle_write(req);
bdrv_aio_writev(req->dev->bs, req->out->sector, &req->qiov,
req->qiov.size / 512, virtio_blk_rw_complete, req);
req = req->next;
}
}