On 2018/11/6 下午2:22, jiangyiwen wrote:
On 2018/11/6 11:38, Jason Wang wrote:
On 2018/11/5 下午3:45, jiangyiwen wrote:
In driver probing, if virtio has VIRTIO_VSOCK_F_MRG_RXBUF feature,
it will fill mergeable rx buffer, support for host send mergeable
rx buffer. It will fill a page everytime to compact with small
packet and big packet.
Signed-off-by: Yiwen Jiang<jiangyiwen@xxxxxxxxxx>
---
include/linux/virtio_vsock.h | 3 ++
net/vmw_vsock/virtio_transport.c | 72 +++++++++++++++++++++++++++++-----------
2 files changed, 56 insertions(+), 19 deletions(-)
diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index e223e26..bf84418 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -14,6 +14,9 @@
#define VIRTIO_VSOCK_MAX_BUF_SIZE 0xFFFFFFFFUL
#define VIRTIO_VSOCK_MAX_PKT_BUF_SIZE (1024 * 64)
+/* Virtio-vsock feature */
+#define VIRTIO_VSOCK_F_MRG_RXBUF 0 /* Host can merge receive buffers. */
+
enum {
VSOCK_VQ_RX = 0, /* for host to guest data */
VSOCK_VQ_TX = 1, /* for guest to host data */
diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index 5d3cce9..2040a9e 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -64,6 +64,7 @@ struct virtio_vsock {
struct virtio_vsock_event event_list[8];
u32 guest_cid;
+ bool mergeable;
};
static struct virtio_vsock *virtio_vsock_get(void)
@@ -256,6 +257,25 @@ static int virtio_transport_send_pkt_loopback(struct virtio_vsock *vsock,
return 0;
}
+static int fill_mergeable_rx_buff(struct virtqueue *vq)
+{
+ void *page = NULL;
+ struct scatterlist sg;
+ int err;
+
+ page = (void *)get_zeroed_page(GFP_KERNEL);
Any reason to use zeroed page?
In previous version, the entire structure of virtio_vsock_pkt is preallocated
in guest use kzalloc, it is a contiguous zeroed physical memory, but host only
need to fill virtio_vsock_hdr size.
However, in mergeable rx buffer version, we only fill a page in vring descriptor
in guest, and I will reserve size of virtio_vsock_pkt in host instead of write
the total size of virtio_vsock_pkt, for the correctness of structure value,
we should set zeroed page in advance.
I may miss something, but it looks to me only the header needs to be zeroed.
+ if (!page)
+ return -ENOMEM;
+
+ sg_init_one(&sg, page, PAGE_SIZE);
FYI, for virtio-net we have several optimizations for mergeable rx buffer:
- skb_page_frag_refill() which can use high order page and reduce the stress of page allocator
You're right, initially I want to use a memory poll to manage the rx buffer,
and then use this in the later optimized patch. Your advice is very great.
- we don't use fixed buffer size, instead we use EWMA to estimate the possible rx buffer size to avoid internal fragmentation
Ok, I analysis the feature and consider add it into my patches.
If we can try to reuse virtio-net driver, we will get those nice features.
Yes, after all virtio-net has a very good ecological environment, and it also
do many performance optimization, it is actually a good idea.
Yes, so my suggestion is to consider to reuse them (unless we found
something that is a real blocker) instead of duplicating codes, features
a bugs.
Thanks
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