On 2019/5/29 上午12:45, Stefano Garzarella wrote:
On Wed, May 15, 2019 at 10:48:44AM +0800, Jason Wang wrote:
On 2019/5/15 上午12:35, Stefano Garzarella wrote:
On Tue, May 14, 2019 at 11:25:34AM +0800, Jason Wang wrote:
On 2019/5/14 上午1:23, Stefano Garzarella wrote:
On Mon, May 13, 2019 at 05:58:53PM +0800, Jason Wang wrote:
On 2019/5/10 下午8:58, Stefano Garzarella wrote:
+static struct virtio_vsock_buf *
+virtio_transport_alloc_buf(struct virtio_vsock_pkt *pkt, bool zero_copy)
+{
+ struct virtio_vsock_buf *buf;
+
+ if (pkt->len == 0)
+ return NULL;
+
+ buf = kzalloc(sizeof(*buf), GFP_KERNEL);
+ if (!buf)
+ return NULL;
+
+ /* If the buffer in the virtio_vsock_pkt is full, we can move it to
+ * the new virtio_vsock_buf avoiding the copy, because we are sure that
+ * we are not use more memory than that counted by the credit mechanism.
+ */
+ if (zero_copy && pkt->len == pkt->buf_len) {
+ buf->addr = pkt->buf;
+ pkt->buf = NULL;
+ } else {
Is the copy still needed if we're just few bytes less? We meet similar issue
for virito-net, and virtio-net solve this by always copy first 128bytes for
big packets.
See receive_big()
I'm seeing, It is more sophisticated.
IIUC, virtio-net allocates a sk_buff with 128 bytes of buffer, then copies the
first 128 bytes, then adds the buffer used to receive the packet as a frag to
the skb.
Yes and the point is if the packet is smaller than 128 bytes the pages will
be recycled.
So it's avoid the overhead of allocation of a large buffer. I got it.
Just a curiosity, why the threshold is 128 bytes?
From its name (GOOD_COPY_LEN), I think it just a value that won't lose much
performance, e.g the size two cachelines.
Jason, Stefan,
since I'm removing the patches to increase the buffers to 64 KiB and I'm
adding a threshold for small packets, I would simplify this patch,
removing the new buffer allocation and copying small packets into the
buffers already queued (if there is a space).
In this way, I should solve the issue of 1 byte packets.
Do you think could be better?
I think so.
Thanks
Thanks,
Stefano
