[PATCHv2 net-next 5/8] vhost: track zero copy failures using DMA length
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2012-10-31 10:31:31
Subsystem:
the rest, virtio host (vhost) · Maintainers:
Linus Torvalds, "Michael S. Tsirkin", Jason Wang
This will be used to disable zerocopy when error rate is high. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- drivers/vhost/vhost.c | 7 ++++--- drivers/vhost/vhost.h | 4 ++++ 2 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 906fd9f..5affce3 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c@@ -425,7 +425,7 @@ int vhost_zerocopy_signal_used(struct vhost_virtqueue *vq) int j = 0; for (i = vq->done_idx; i != vq->upend_idx; i = (i + 1) % UIO_MAXIOV) { - if ((vq->heads[i].len == VHOST_DMA_DONE_LEN)) { + if (VHOST_DMA_IS_DONE(vq->heads[i].len)) { vq->heads[i].len = VHOST_DMA_CLEAR_LEN; vhost_add_used_and_signal(vq->dev, vq, vq->heads[i].id, 0);
@@ -1600,13 +1600,14 @@ void vhost_ubuf_put_and_wait(struct vhost_ubuf_ref *ubufs) kfree(ubufs); } -void vhost_zerocopy_callback(struct ubuf_info *ubuf, int zerocopy_status) +void vhost_zerocopy_callback(struct ubuf_info *ubuf, int status) { struct vhost_ubuf_ref *ubufs = ubuf->ctx; struct vhost_virtqueue *vq = ubufs->vq; vhost_poll_queue(&vq->poll); /* set len to mark this desc buffers done DMA */ - vq->heads[ubuf->desc].len = VHOST_DMA_DONE_LEN; + vq->heads[ubuf->desc].len = status ? + VHOST_DMA_FAILED_LEN : VHOST_DMA_DONE_LEN; kref_put(&ubufs->kref, vhost_zerocopy_done_signal); }
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index ad72a1f..6fdf31d 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h@@ -17,6 +17,8 @@ * For transmit, used buffer len is unused; we override it to track buffer * status internally; used for zerocopy tx only. */ +/* Lower device DMA failed */ +#define VHOST_DMA_FAILED_LEN 3 /* Lower device DMA done */ #define VHOST_DMA_DONE_LEN 2 /* Lower device DMA in progress */
@@ -24,6 +26,8 @@ /* Buffer unused */ #define VHOST_DMA_CLEAR_LEN 0 +#define VHOST_DMA_IS_DONE(len) ((len) >= VHOST_DMA_DONE_LEN) + struct vhost_device; struct vhost_work;
--
MST