On Mon, Apr 22, 2013 at 08:32:27PM -0400, Sasha Levin wrote:
> Support mergable rx buffers for virtio-net. This helps reduce the amount
> of memory the guest kernel has to allocate per rx vq.
With this, we always do an extra copy of the rx data into a linear buffer.
I am thinking about whether we should keep the non MRG_RXBUF code. For
tap use case, it is fine, user can use vhost. But for uip use case, we
can not use vhost.
> Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
> ---
> tools/kvm/include/kvm/uip.h | 4 ++--
> tools/kvm/include/kvm/util.h | 3 +++
> tools/kvm/net/uip/core.c | 54 +++++---------------------------------------
> tools/kvm/net/uip/tcp.c | 2 +-
> tools/kvm/net/uip/udp.c | 2 +-
> tools/kvm/util/util.c | 15 ++++++++++++
> tools/kvm/virtio/net.c | 37 ++++++++++++++++++++++--------
> 7 files changed, 55 insertions(+), 62 deletions(-)
>
> diff --git a/tools/kvm/include/kvm/uip.h b/tools/kvm/include/kvm/uip.h
> index ac248d2..fa82f10 100644
> --- a/tools/kvm/include/kvm/uip.h
> +++ b/tools/kvm/include/kvm/uip.h
> @@ -252,7 +252,7 @@ struct uip_tcp_socket {
> };
>
> struct uip_tx_arg {
> - struct virtio_net_hdr *vnet;
> + struct virtio_net_hdr_mrg_rxbuf *vnet;
> struct uip_info *info;
> struct uip_eth *eth;
> int vnet_len;
> @@ -332,7 +332,7 @@ static inline u16 uip_eth_hdrlen(struct uip_eth *eth)
> }
>
> int uip_tx(struct iovec *iov, u16 out, struct uip_info *info);
> -int uip_rx(struct iovec *iov, u16 in, struct uip_info *info);
> +int uip_rx(unsigned char *buffer, u32 length, struct uip_info *info);
> int uip_init(struct uip_info *info);
>
> int uip_tx_do_ipv4_udp_dhcp(struct uip_tx_arg *arg);
> diff --git a/tools/kvm/include/kvm/util.h b/tools/kvm/include/kvm/util.h
> index 0df9f0d..6f8ac83 100644
> --- a/tools/kvm/include/kvm/util.h
> +++ b/tools/kvm/include/kvm/util.h
> @@ -22,6 +22,7 @@
> #include <sys/param.h>
> #include <sys/types.h>
> #include <linux/types.h>
> +#include <sys/uio.h>
>
> #ifdef __GNUC__
> #define NORETURN __attribute__((__noreturn__))
> @@ -94,4 +95,6 @@ struct kvm;
> void *mmap_hugetlbfs(struct kvm *kvm, const char *htlbfs_path, u64 size);
> void *mmap_anon_or_hugetlbfs(struct kvm *kvm, const char *hugetlbfs_path, u64 size);
>
> +int memcpy_toiovecend(const struct iovec *iov, int iovlen, unsigned char *kdata, size_t len);
> +
> #endif /* KVM__UTIL_H */
> diff --git a/tools/kvm/net/uip/core.c b/tools/kvm/net/uip/core.c
> index 4e5bb82..d9e9993 100644
> --- a/tools/kvm/net/uip/core.c
> +++ b/tools/kvm/net/uip/core.c
> @@ -7,7 +7,7 @@
>
> int uip_tx(struct iovec *iov, u16 out, struct uip_info *info)
> {
> - struct virtio_net_hdr *vnet;
> + struct virtio_net_hdr_mrg_rxbuf *vnet;
> struct uip_tx_arg arg;
> int eth_len, vnet_len;
> struct uip_eth *eth;
> @@ -74,63 +74,21 @@ int uip_tx(struct iovec *iov, u16 out, struct uip_info *info)
> return vnet_len + eth_len;
> }
>
> -int uip_rx(struct iovec *iov, u16 in, struct uip_info *info)
> +int uip_rx(unsigned char *buffer, u32 length, struct uip_info *info)
> {
> - struct virtio_net_hdr *vnet;
> - struct uip_eth *eth;
> struct uip_buf *buf;
> - int vnet_len;
> - int eth_len;
> - char *p;
> int len;
> - int cnt;
> - int i;
>
> /*
> * Sleep until there is a buffer for guest
> */
> buf = uip_buf_get_used(info);
>
> - /*
> - * Fill device to guest buffer, vnet hdr fisrt
> - */
> - vnet_len = iov[0].iov_len;
> - vnet = iov[0].iov_base;
> - if (buf->vnet_len > vnet_len) {
> - len = -1;
> - goto out;
> - }
> - memcpy(vnet, buf->vnet, buf->vnet_len);
> -
> - /*
> - * Then, the real eth data
> - * Note: Be sure buf->eth_len is not bigger than the buffer len that guest provides
> - */
> - cnt = buf->eth_len;
> - p = buf->eth;
> - for (i = 1; i < in; i++) {
> - eth_len = iov[i].iov_len;
> - eth = iov[i].iov_base;
> - if (cnt > eth_len) {
> - memcpy(eth, p, eth_len);
> - cnt -= eth_len;
> - p += eth_len;
> - } else {
> - memcpy(eth, p, cnt);
> - cnt -= cnt;
> - break;
> - }
> - }
> -
> - if (cnt) {
> - pr_warning("uip_rx error");
> - len = -1;
> - goto out;
> - }
> + memcpy(buffer, buf->vnet, buf->vnet_len);
> + memcpy(buffer + buf->vnet_len, buf->eth, buf->eth_len);
>
> len = buf->vnet_len + buf->eth_len;
>
> -out:
> uip_buf_set_free(info, buf);
> return len;
> }
> @@ -172,8 +130,8 @@ int uip_init(struct uip_info *info)
> }
>
> list_for_each_entry(buf, buf_head, list) {
> - buf->vnet = malloc(sizeof(struct virtio_net_hdr));
> - buf->vnet_len = sizeof(struct virtio_net_hdr);
> + buf->vnet = malloc(sizeof(struct virtio_net_hdr_mrg_rxbuf));
> + buf->vnet_len = sizeof(struct virtio_net_hdr_mrg_rxbuf);
> buf->eth = malloc(1024*64 + sizeof(struct uip_pseudo_hdr));
> buf->eth_len = 1024*64 + sizeof(struct uip_pseudo_hdr);
>
> diff --git a/tools/kvm/net/uip/tcp.c b/tools/kvm/net/uip/tcp.c
> index 9044f40..a99b95e 100644
> --- a/tools/kvm/net/uip/tcp.c
> +++ b/tools/kvm/net/uip/tcp.c
> @@ -153,7 +153,7 @@ static int uip_tcp_payload_send(struct uip_tcp_socket *sk, u8 flag, u16 payload_
> /*
> * virtio_net_hdr
> */
> - buf->vnet_len = sizeof(struct virtio_net_hdr);
> + buf->vnet_len = sizeof(struct virtio_net_hdr_mrg_rxbuf);
> memset(buf->vnet, 0, buf->vnet_len);
>
> buf->eth_len = ntohs(ip2->len) + uip_eth_hdrlen(&ip2->eth);
> diff --git a/tools/kvm/net/uip/udp.c b/tools/kvm/net/uip/udp.c
> index 31c417c..083c221 100644
> --- a/tools/kvm/net/uip/udp.c
> +++ b/tools/kvm/net/uip/udp.c
> @@ -142,7 +142,7 @@ int uip_udp_make_pkg(struct uip_info *info, struct uip_udp_socket *sk, struct ui
> /*
> * virtio_net_hdr
> */
> - buf->vnet_len = sizeof(struct virtio_net_hdr);
> + buf->vnet_len = sizeof(struct virtio_net_hdr_mrg_rxbuf);
> memset(buf->vnet, 0, buf->vnet_len);
>
> buf->eth_len = ntohs(ip2->len) + uip_eth_hdrlen(&ip2->eth);
> diff --git a/tools/kvm/util/util.c b/tools/kvm/util/util.c
> index c11a15a..4e0069c 100644
> --- a/tools/kvm/util/util.c
> +++ b/tools/kvm/util/util.c
> @@ -9,6 +9,7 @@
> #include <sys/mman.h>
> #include <sys/stat.h>
> #include <sys/statfs.h>
> +#include <linux/kernel.h>
>
> static void report(const char *prefix, const char *err, va_list params)
> {
> @@ -131,3 +132,17 @@ void *mmap_anon_or_hugetlbfs(struct kvm *kvm, const char *hugetlbfs_path, u64 si
> return mmap(NULL, size, PROT_RW, MAP_ANON_NORESERVE, -1, 0);
> }
> }
> +
> +int memcpy_toiovecend(const struct iovec *iov, int iovlen, unsigned char *kdata, size_t len)
> +{
> + size_t copy, start_len = len;
> +
> + for (; len > 0 && iovlen > 0; ++iov, --iovlen) {
> + copy = min(iov->iov_len, len);
> + memcpy(iov->iov_base, kdata, copy);
> + kdata += copy;
> + len -= copy;
> + }
> +
> + return start_len - len;
> +}
> diff --git a/tools/kvm/virtio/net.c b/tools/kvm/virtio/net.c
> index c0a8f12..c99c5a6 100644
> --- a/tools/kvm/virtio/net.c
> +++ b/tools/kvm/virtio/net.c
> @@ -32,8 +32,8 @@
> struct net_dev;
>
> struct net_dev_operations {
> - int (*rx)(struct iovec *iov, u16 in, struct net_dev *ndev);
> - int (*tx)(struct iovec *iov, u16 in, struct net_dev *ndev);
> + int (*rx)(unsigned char *buffer, u32 length, struct net_dev *ndev);
> + int (*tx)(struct iovec *iov, u16 out, struct net_dev *ndev);
> };
>
> struct net_dev {
> @@ -63,6 +63,8 @@ struct net_dev {
> static LIST_HEAD(ndevs);
> static int compat_id = -1;
>
> +#define MAX_PACKET_SIZE ((u16)(-1))
Why 64KB - 1? The package can be 65550 bytes which is max TCP or UDP
plus 14 bytes eth header.
> +
> static void *virtio_net_rx_thread(void *p)
> {
> struct iovec iov[VIRTIO_NET_QUEUE_SIZE];
> @@ -90,9 +92,23 @@ static void *virtio_net_rx_thread(void *p)
> mutex_unlock(&ndev->io_lock[id]);
>
> while (virt_queue__available(vq)) {
> + unsigned char buffer[MAX_PACKET_SIZE];
The buffer size should at least be:
MAX_PACKET_SIZE + sizeof(struct virtio_net_hdr_mrg_rxbuf)
> + struct virtio_net_hdr_mrg_rxbuf *hdr;
> +
> + len = ndev->ops->rx(buffer, MAX_PACKET_SIZE, ndev);
> head = virt_queue__get_iov(vq, iov, &out, &in, kvm);
> - len = ndev->ops->rx(iov, in, ndev);
> - virt_queue__set_used_elem(vq, head, len);
> + hdr = (void *)iov[0].iov_base;
> + while (len) {
> + int copied;
> +
> + copied = memcpy_toiovecend(iov, in, buffer, len);
> + len -= copied;
> + hdr->num_buffers++;
> + virt_queue__set_used_elem(vq, head, copied);
> + if (len == 0)
> + break;
> + head = virt_queue__get_iov(vq, iov, &out, &in, kvm);
Here, need to check if we still have available buffer from guest. If not
need to wait for it.
> + }
>
> /* We should interrupt guest right now, otherwise latency is huge. */
> if (virtio_queue__should_signal(vq))
> @@ -241,7 +257,7 @@ static bool virtio_net__tap_init(const struct virtio_net_params *params,
> goto fail;
> }
>
> - hdr_len = sizeof(struct virtio_net_hdr);
> + hdr_len = sizeof(struct virtio_net_hdr_mrg_rxbuf);
> if (ioctl(ndev->tap_fd, TUNSETVNETHDRSZ, &hdr_len) < 0)
> pr_warning("Config tap device TUNSETVNETHDRSZ error");
>
> @@ -300,9 +316,9 @@ static inline int tap_ops_tx(struct iovec *iov, u16 out, struct net_dev *ndev)
> return writev(ndev->tap_fd, iov, out);
> }
>
> -static inline int tap_ops_rx(struct iovec *iov, u16 in, struct net_dev *ndev)
> +static inline int tap_ops_rx(unsigned char *buffer, u32 length, struct net_dev *ndev)
> {
> - return readv(ndev->tap_fd, iov, in);
> + return read(ndev->tap_fd, buffer, length);
> }
>
> static inline int uip_ops_tx(struct iovec *iov, u16 out, struct net_dev *ndev)
> @@ -310,9 +326,9 @@ static inline int uip_ops_tx(struct iovec *iov, u16 out, struct net_dev *ndev)
> return uip_tx(iov, out, &ndev->info);
> }
>
> -static inline int uip_ops_rx(struct iovec *iov, u16 in, struct net_dev *ndev)
> +static inline int uip_ops_rx(unsigned char *buffer, u32 length, struct net_dev *ndev)
> {
> - return uip_rx(iov, in, &ndev->info);
> + return uip_rx(buffer, length, &ndev->info);
> }
>
> static struct net_dev_operations tap_ops = {
> @@ -347,7 +363,8 @@ static u32 get_host_features(struct kvm *kvm, void *dev)
> | 1UL << VIRTIO_RING_F_EVENT_IDX
> | 1UL << VIRTIO_RING_F_INDIRECT_DESC
> | 1UL << VIRTIO_NET_F_CTRL_VQ
> - | 1UL << (ndev->queue_pairs > 1 ? VIRTIO_NET_F_MQ : 0);
> + | 1UL << (ndev->queue_pairs > 1 ? VIRTIO_NET_F_MQ : 0)
> + | 1UL << VIRTIO_NET_F_MRG_RXBUF;
> }
>
> static void set_guest_features(struct kvm *kvm, void *dev, u32 features)
> --
> 1.8.2.1
>
--
Asias
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