Re: [PATCH v3 17/18] vhost: don't bother copying iovecs in handle_rx(), kill memcpy_toiovecend()
> if (likely(mergeable) &&
> - memcpy_toiovecend(nvq->hdr, (unsigned char *)&headcount,
> - offsetof(typeof(hdr), num_buffers),
> - sizeof hdr.num_buffers)) {
> + copy_to_iter(&headcount, 2, &fixup) != 2) {
> vq_err(vq, "Failed num_buffers write");
> vhost_discard_vq_desc(vq, headcount);
> break;
BTW this will have to be re-based on top of
http://mid.gmane.org/1422896842-19186-1-git-send-email-...@redhat.com
taking byte-swap into account.
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Re: [PATCH v3 17/18] vhost: don't bother copying iovecs in handle_rx(), kill memcpy_toiovecend()
On Wed, Feb 04, 2015 at 06:40:08AM +, Al Viro wrote:
> From: Al Viro
>
> Cc: Michael S. Tsirkin
> Cc: kvm@vger.kernel.org
> Cc: virtualizat...@lists.linux-foundation.org
> Signed-off-by: Al Viro
Acked-by: Michael S. Tsirkin
> ---
> drivers/vhost/net.c | 82
> +++--
> include/linux/uio.h | 3 --
> lib/iovec.c | 26 -
> 3 files changed, 23 insertions(+), 88 deletions(-)
>
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index d86cc9b..e022cc4 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -84,10 +84,6 @@ struct vhost_net_ubuf_ref {
>
> struct vhost_net_virtqueue {
> struct vhost_virtqueue vq;
> - /* hdr is used to store the virtio header.
> - * Since each iovec has >= 1 byte length, we never need more than
> - * header length entries to store the header. */
> - struct iovec hdr[sizeof(struct virtio_net_hdr_mrg_rxbuf)];
> size_t vhost_hlen;
> size_t sock_hlen;
> /* vhost zerocopy support fields below: */
> @@ -235,44 +231,6 @@ static bool vhost_sock_zcopy(struct socket *sock)
> sock_flag(sock->sk, SOCK_ZEROCOPY);
> }
>
> -/* Pop first len bytes from iovec. Return number of segments used. */
> -static int move_iovec_hdr(struct iovec *from, struct iovec *to,
> - size_t len, int iov_count)
> -{
> - int seg = 0;
> - size_t size;
> -
> - while (len && seg < iov_count) {
> - size = min(from->iov_len, len);
> - to->iov_base = from->iov_base;
> - to->iov_len = size;
> - from->iov_len -= size;
> - from->iov_base += size;
> - len -= size;
> - ++from;
> - ++to;
> - ++seg;
> - }
> - return seg;
> -}
> -/* Copy iovec entries for len bytes from iovec. */
> -static void copy_iovec_hdr(const struct iovec *from, struct iovec *to,
> -size_t len, int iovcount)
> -{
> - int seg = 0;
> - size_t size;
> -
> - while (len && seg < iovcount) {
> - size = min(from->iov_len, len);
> - to->iov_base = from->iov_base;
> - to->iov_len = size;
> - len -= size;
> - ++from;
> - ++to;
> - ++seg;
> - }
> -}
> -
> /* In case of DMA done not in order in lower device driver for some reason.
> * upend_idx is used to track end of used idx, done_idx is used to track head
> * of used idx. Once lower device DMA done contiguously, we will signal KVM
> @@ -570,9 +528,9 @@ static void handle_rx(struct vhost_net *net)
> .msg_controllen = 0,
> .msg_flags = MSG_DONTWAIT,
> };
> - struct virtio_net_hdr_mrg_rxbuf hdr = {
> - .hdr.flags = 0,
> - .hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
> + struct virtio_net_hdr hdr = {
> + .flags = 0,
> + .gso_type = VIRTIO_NET_HDR_GSO_NONE
> };
> size_t total_len = 0;
> int err, mergeable;
> @@ -580,6 +538,7 @@ static void handle_rx(struct vhost_net *net)
> size_t vhost_hlen, sock_hlen;
> size_t vhost_len, sock_len;
> struct socket *sock;
> + struct iov_iter fixup;
>
> mutex_lock(&vq->mutex);
> sock = vq->private_data;
> @@ -624,14 +583,19 @@ static void handle_rx(struct vhost_net *net)
> break;
> }
> /* We don't need to be notified again. */
> - if (unlikely((vhost_hlen)))
> - /* Skip header. TODO: support TSO. */
> - move_iovec_hdr(vq->iov, nvq->hdr, vhost_hlen, in);
> - else
> - /* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF:
> - * needed because recvmsg can modify msg_iov. */
> - copy_iovec_hdr(vq->iov, nvq->hdr, sock_hlen, in);
> - iov_iter_init(&msg.msg_iter, READ, vq->iov, in, sock_len);
> + iov_iter_init(&msg.msg_iter, READ, vq->iov, in, vhost_len);
> + fixup = msg.msg_iter;
> + if (unlikely((vhost_hlen))) {
> + /* We will supply the header ourselves
> + * TODO: support TSO.
> + */
> + iov_iter_advance(&msg.msg_iter, vhost_hlen);
> + } else {
> + /* It'll come from socket; we'll need to patch
> + * ->num_buffers over if VIRTIO_NET_F_MRG_RXBUF
> + */
> + iov_iter_advance(&fixup, sizeof(hdr));
> + }
> err = sock->ops->recvmsg(NULL, sock, &msg,
>sock_len, MSG_DONTWAIT | MSG_TRUNC);
> /* Userspace might have consumed the packet meanwhile:
> @@ -643,18 +607,18 @@ static void handle_rx(struct vhost_net *net)
> vhost_discard_vq_desc(vq, h
[PATCH v3 17/18] vhost: don't bother copying iovecs in handle_rx(), kill memcpy_toiovecend()
From: Al Viro
Cc: Michael S. Tsirkin
Cc: kvm@vger.kernel.org
Cc: virtualizat...@lists.linux-foundation.org
Signed-off-by: Al Viro
---
drivers/vhost/net.c | 82 +++--
include/linux/uio.h | 3 --
lib/iovec.c | 26 -
3 files changed, 23 insertions(+), 88 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index d86cc9b..e022cc4 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -84,10 +84,6 @@ struct vhost_net_ubuf_ref {
struct vhost_net_virtqueue {
struct vhost_virtqueue vq;
- /* hdr is used to store the virtio header.
-* Since each iovec has >= 1 byte length, we never need more than
-* header length entries to store the header. */
- struct iovec hdr[sizeof(struct virtio_net_hdr_mrg_rxbuf)];
size_t vhost_hlen;
size_t sock_hlen;
/* vhost zerocopy support fields below: */
@@ -235,44 +231,6 @@ static bool vhost_sock_zcopy(struct socket *sock)
sock_flag(sock->sk, SOCK_ZEROCOPY);
}
-/* Pop first len bytes from iovec. Return number of segments used. */
-static int move_iovec_hdr(struct iovec *from, struct iovec *to,
- size_t len, int iov_count)
-{
- int seg = 0;
- size_t size;
-
- while (len && seg < iov_count) {
- size = min(from->iov_len, len);
- to->iov_base = from->iov_base;
- to->iov_len = size;
- from->iov_len -= size;
- from->iov_base += size;
- len -= size;
- ++from;
- ++to;
- ++seg;
- }
- return seg;
-}
-/* Copy iovec entries for len bytes from iovec. */
-static void copy_iovec_hdr(const struct iovec *from, struct iovec *to,
- size_t len, int iovcount)
-{
- int seg = 0;
- size_t size;
-
- while (len && seg < iovcount) {
- size = min(from->iov_len, len);
- to->iov_base = from->iov_base;
- to->iov_len = size;
- len -= size;
- ++from;
- ++to;
- ++seg;
- }
-}
-
/* In case of DMA done not in order in lower device driver for some reason.
* upend_idx is used to track end of used idx, done_idx is used to track head
* of used idx. Once lower device DMA done contiguously, we will signal KVM
@@ -570,9 +528,9 @@ static void handle_rx(struct vhost_net *net)
.msg_controllen = 0,
.msg_flags = MSG_DONTWAIT,
};
- struct virtio_net_hdr_mrg_rxbuf hdr = {
- .hdr.flags = 0,
- .hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
+ struct virtio_net_hdr hdr = {
+ .flags = 0,
+ .gso_type = VIRTIO_NET_HDR_GSO_NONE
};
size_t total_len = 0;
int err, mergeable;
@@ -580,6 +538,7 @@ static void handle_rx(struct vhost_net *net)
size_t vhost_hlen, sock_hlen;
size_t vhost_len, sock_len;
struct socket *sock;
+ struct iov_iter fixup;
mutex_lock(&vq->mutex);
sock = vq->private_data;
@@ -624,14 +583,19 @@ static void handle_rx(struct vhost_net *net)
break;
}
/* We don't need to be notified again. */
- if (unlikely((vhost_hlen)))
- /* Skip header. TODO: support TSO. */
- move_iovec_hdr(vq->iov, nvq->hdr, vhost_hlen, in);
- else
- /* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF:
-* needed because recvmsg can modify msg_iov. */
- copy_iovec_hdr(vq->iov, nvq->hdr, sock_hlen, in);
- iov_iter_init(&msg.msg_iter, READ, vq->iov, in, sock_len);
+ iov_iter_init(&msg.msg_iter, READ, vq->iov, in, vhost_len);
+ fixup = msg.msg_iter;
+ if (unlikely((vhost_hlen))) {
+ /* We will supply the header ourselves
+* TODO: support TSO.
+*/
+ iov_iter_advance(&msg.msg_iter, vhost_hlen);
+ } else {
+ /* It'll come from socket; we'll need to patch
+* ->num_buffers over if VIRTIO_NET_F_MRG_RXBUF
+*/
+ iov_iter_advance(&fixup, sizeof(hdr));
+ }
err = sock->ops->recvmsg(NULL, sock, &msg,
sock_len, MSG_DONTWAIT | MSG_TRUNC);
/* Userspace might have consumed the packet meanwhile:
@@ -643,18 +607,18 @@ static void handle_rx(struct vhost_net *net)
vhost_discard_vq_desc(vq, headcount);
continue;
}
+ /* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
if (unlikely(vhost_hl
