diff options
| author | Jason Wang <jasowang@redhat.com> | 2025-07-01 09:03:52 +0800 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2025-07-02 15:29:46 -0700 |
| commit | 97b2409f28e0d69e5ab62df0798be8bd744a770f (patch) | |
| tree | bdf07859e5a8f978c4e8b4a47226a8135c315234 | |
| parent | 4d313f2bd22213caace3fe4fb02977b527f9c6c3 (diff) | |
vhost-net: reduce one userspace copy when building XDP buff
We used to do twice copy_from_iter() to copy virtio-net and packet
separately. This introduce overheads for userspace access hardening as
well as SMAP (for x86 it's stac/clac). So this patch tries to use one
copy_from_iter() to copy them once and move the virtio-net header
afterwards to reduce overheads.
Testpmd + vhost_net shows 10% improvement from 5.45Mpps to 6.0Mpps.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://patch.msgid.link/20250701010352.74515-2-jasowang@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | drivers/vhost/net.c | 16 |
1 files changed, 6 insertions, 10 deletions
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 777eb6193985..9dbd88eb9ff4 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -690,13 +690,13 @@ static int vhost_net_build_xdp(struct vhost_net_virtqueue *nvq, if (unlikely(!buf)) return -ENOMEM; - copied = copy_from_iter(buf, sock_hlen, from); - if (copied != sock_hlen) { + copied = copy_from_iter(buf + pad - sock_hlen, len, from); + if (copied != len) { ret = -EFAULT; goto err; } - gso = buf; + gso = buf + pad - sock_hlen; if (!sock_hlen) memset(buf, 0, pad); @@ -715,15 +715,11 @@ static int vhost_net_build_xdp(struct vhost_net_virtqueue *nvq, } } - len -= sock_hlen; - copied = copy_from_iter(buf + pad, len, from); - if (copied != len) { - ret = -EFAULT; - goto err; - } + /* pad contains sock_hlen */ + memcpy(buf, buf + pad - sock_hlen, sock_hlen); xdp_init_buff(xdp, buflen, NULL); - xdp_prepare_buff(xdp, buf, pad, len, true); + xdp_prepare_buff(xdp, buf, pad, len - sock_hlen, true); ++nvq->batched_xdp; |