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Message-ID: <20231201120208.15080-5-linyunsheng@huawei.com>
Date: Fri, 1 Dec 2023 20:02:05 +0800
From: Yunsheng Lin <linyunsheng@...wei.com>
To: <davem@...emloft.net>, <kuba@...nel.org>, <pabeni@...hat.com>
CC: <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
Yunsheng Lin <linyunsheng@...wei.com>,
"Michael S. Tsirkin" <mst@...hat.com>,
Jason Wang <jasowang@...hat.com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Jesper Dangaard Brouer <hawk@...nel.org>,
John Fastabend <john.fastabend@...il.com>,
<kvm@...r.kernel.org>, <virtualization@...ts.linux.dev>,
<bpf@...r.kernel.org>
Subject: [PATCH RFC 4/6] vhost/net: remove vhost_net_page_frag_refill()
The page frag in vhost_net_page_frag_refill() uses the
'struct page_frag' from skb_page_frag_refill(), but it's
implementation is similar to page_frag_alloc_align() now.
This patch removes vhost_net_page_frag_refill() by using
'struct page_frag_cache' instead of 'struct page_frag',
and allocating frag using page_frag_alloc_align().
The added benefit is that not only unifying the page frag
implementation a little, but also having about 0.5% performance
boost testing by using the vhost_net_test introduced in the
last patch.
Signed-off-by: Yunsheng Lin <linyunsheng@...wei.com>
---
drivers/vhost/net.c | 93 ++++++++++++++-------------------------------
1 file changed, 29 insertions(+), 64 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index e574e21cc0ca..805e11d598e4 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -141,10 +141,8 @@ struct vhost_net {
unsigned tx_zcopy_err;
/* Flush in progress. Protected by tx vq lock. */
bool tx_flush;
- /* Private page frag */
- struct page_frag page_frag;
- /* Refcount bias of page frag */
- int refcnt_bias;
+ /* Private page frag cache */
+ struct page_frag_cache pf_cache;
};
static unsigned vhost_net_zcopy_mask __read_mostly;
@@ -655,41 +653,6 @@ static bool tx_can_batch(struct vhost_virtqueue *vq, size_t total_len)
!vhost_vq_avail_empty(vq->dev, vq);
}
-static bool vhost_net_page_frag_refill(struct vhost_net *net, unsigned int sz,
- struct page_frag *pfrag, gfp_t gfp)
-{
- if (pfrag->page) {
- if (pfrag->offset + sz <= pfrag->size)
- return true;
- __page_frag_cache_drain(pfrag->page, net->refcnt_bias);
- }
-
- pfrag->offset = 0;
- net->refcnt_bias = 0;
- if (SKB_FRAG_PAGE_ORDER) {
- /* Avoid direct reclaim but allow kswapd to wake */
- pfrag->page = alloc_pages((gfp & ~__GFP_DIRECT_RECLAIM) |
- __GFP_COMP | __GFP_NOWARN |
- __GFP_NORETRY | __GFP_NOMEMALLOC,
- SKB_FRAG_PAGE_ORDER);
- if (likely(pfrag->page)) {
- pfrag->size = PAGE_SIZE << SKB_FRAG_PAGE_ORDER;
- goto done;
- }
- }
- pfrag->page = alloc_page(gfp);
- if (likely(pfrag->page)) {
- pfrag->size = PAGE_SIZE;
- goto done;
- }
- return false;
-
-done:
- net->refcnt_bias = USHRT_MAX;
- page_ref_add(pfrag->page, USHRT_MAX - 1);
- return true;
-}
-
#define VHOST_NET_RX_PAD (NET_IP_ALIGN + NET_SKB_PAD)
static int vhost_net_build_xdp(struct vhost_net_virtqueue *nvq,
@@ -699,7 +662,6 @@ static int vhost_net_build_xdp(struct vhost_net_virtqueue *nvq,
struct vhost_net *net = container_of(vq->dev, struct vhost_net,
dev);
struct socket *sock = vhost_vq_get_backend(vq);
- struct page_frag *alloc_frag = &net->page_frag;
struct virtio_net_hdr *gso;
struct xdp_buff *xdp = &nvq->xdp[nvq->batched_xdp];
struct tun_xdp_hdr *hdr;
@@ -710,6 +672,7 @@ static int vhost_net_build_xdp(struct vhost_net_virtqueue *nvq,
int sock_hlen = nvq->sock_hlen;
void *buf;
int copied;
+ int ret;
if (unlikely(len < nvq->sock_hlen))
return -EFAULT;
@@ -719,18 +682,17 @@ static int vhost_net_build_xdp(struct vhost_net_virtqueue *nvq,
return -ENOSPC;
buflen += SKB_DATA_ALIGN(len + pad);
- alloc_frag->offset = ALIGN((u64)alloc_frag->offset, SMP_CACHE_BYTES);
- if (unlikely(!vhost_net_page_frag_refill(net, buflen,
- alloc_frag, GFP_KERNEL)))
+ buf = page_frag_alloc_align(&net->pf_cache, buflen, GFP_KERNEL,
+ SMP_CACHE_BYTES);
+ if (unlikely(!buf))
return -ENOMEM;
- buf = (char *)page_address(alloc_frag->page) + alloc_frag->offset;
- copied = copy_page_from_iter(alloc_frag->page,
- alloc_frag->offset +
- offsetof(struct tun_xdp_hdr, gso),
- sock_hlen, from);
- if (copied != sock_hlen)
- return -EFAULT;
+ copied = copy_from_iter(buf + offsetof(struct tun_xdp_hdr, gso),
+ sock_hlen, from);
+ if (copied != sock_hlen) {
+ ret = -EFAULT;
+ goto err;
+ }
hdr = buf;
gso = &hdr->gso;
@@ -743,27 +705,30 @@ static int vhost_net_build_xdp(struct vhost_net_virtqueue *nvq,
vhost16_to_cpu(vq, gso->csum_start) +
vhost16_to_cpu(vq, gso->csum_offset) + 2);
- if (vhost16_to_cpu(vq, gso->hdr_len) > len)
- return -EINVAL;
+ if (vhost16_to_cpu(vq, gso->hdr_len) > len) {
+ ret = -EINVAL;
+ goto err;
+ }
}
len -= sock_hlen;
- copied = copy_page_from_iter(alloc_frag->page,
- alloc_frag->offset + pad,
- len, from);
- if (copied != len)
- return -EFAULT;
+ copied = copy_from_iter(buf + pad, len, from);
+ if (copied != len) {
+ ret = -EFAULT;
+ goto err;
+ }
xdp_init_buff(xdp, buflen, NULL);
xdp_prepare_buff(xdp, buf, pad, len, true);
hdr->buflen = buflen;
- --net->refcnt_bias;
- alloc_frag->offset += buflen;
-
++nvq->batched_xdp;
return 0;
+
+err:
+ page_frag_free(buf);
+ return ret;
}
static void handle_tx_copy(struct vhost_net *net, struct socket *sock)
@@ -1353,8 +1318,7 @@ static int vhost_net_open(struct inode *inode, struct file *f)
vqs[VHOST_NET_VQ_RX]);
f->private_data = n;
- n->page_frag.page = NULL;
- n->refcnt_bias = 0;
+ n->pf_cache.va = NULL;
return 0;
}
@@ -1422,8 +1386,9 @@ static int vhost_net_release(struct inode *inode, struct file *f)
kfree(n->vqs[VHOST_NET_VQ_RX].rxq.queue);
kfree(n->vqs[VHOST_NET_VQ_TX].xdp);
kfree(n->dev.vqs);
- if (n->page_frag.page)
- __page_frag_cache_drain(n->page_frag.page, n->refcnt_bias);
+ if (n->pf_cache.va)
+ __page_frag_cache_drain(virt_to_head_page(n->pf_cache.va),
+ n->pf_cache.pagecnt_bias);
kvfree(n);
return 0;
}
--
2.33.0
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