Re: [PATCH v2 8/8] vsock/virtio: make the RX buffer size tunable

[Jason Wang]

On 2019/5/13 下午6:05, Jason Wang wrote:

On 2019/5/10 下午8:58, Stefano Garzarella wrote:
The RX buffer size determines the memory consumption of the
vsock/virtio guest driver, so we make it tunable through
a module parameter.

The size allowed are between 4 KB and 64 KB in order to be
compatible with old host drivers.

Suggested-by: Stefan Hajnoczi <stefa...@redhat.com>
Signed-off-by: Stefano Garzarella <sgarz...@redhat.com>


I don't see much value of doing this through kernel command line. We 
should deal with them automatically like what virtio-net did. Or even 
a module parameter is better.

Thanks


Sorry, I misread the patch. But even module parameter is something not 
flexible enough. We should deal with them transparently.

Thanks




---
  include/linux/virtio_vsock.h     |  1 +
  net/vmw_vsock/virtio_transport.c | 27 ++++++++++++++++++++++++++-
  2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index 5a9d25be72df..b9f8c3d91f80 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -13,6 +13,7 @@
  #define VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE    (1024 * 64)
  #define VIRTIO_VSOCK_MAX_BUF_SIZE        0xFFFFFFFFUL
  #define VIRTIO_VSOCK_MAX_PKT_BUF_SIZE        (1024 * 64)
+#define VIRTIO_VSOCK_MIN_PKT_BUF_SIZE        (1024 * 4)
    enum {
      VSOCK_VQ_RX     = 0, /* for host to guest data */
diff --git a/net/vmw_vsock/virtio_transport.c 
b/net/vmw_vsock/virtio_transport.c
index af1d2ce12f54..732398b4e28f 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -66,6 +66,31 @@ struct virtio_vsock {
      u32 guest_cid;
  };
  +static unsigned int rx_buf_size = VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE;
+
+static int param_set_rx_buf_size(const char *val, const struct 
kernel_param *kp)
+{
+    unsigned int size;
+    int ret;
+
+    ret = kstrtouint(val, 0, &size);
+    if (ret)
+        return ret;
+
+    if (size < VIRTIO_VSOCK_MIN_PKT_BUF_SIZE ||
+        size > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE)
+        return -EINVAL;
+
+    return param_set_uint(val, kp);
+};
+
+static const struct kernel_param_ops param_ops_rx_buf_size = {
+    .set = param_set_rx_buf_size,
+    .get = param_get_uint,
+};
+
+module_param_cb(rx_buf_size, &param_ops_rx_buf_size, &rx_buf_size, 
0644);
+
  static struct virtio_vsock *virtio_vsock_get(void)
  {
      return the_virtio_vsock;
@@ -261,7 +286,7 @@ virtio_transport_cancel_pkt(struct vsock_sock *vsk)
    static void virtio_vsock_rx_fill(struct virtio_vsock *vsock)
  {
-    int buf_len = VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE;
+    int buf_len = rx_buf_size;
      struct virtio_vsock_pkt *pkt;
      struct scatterlist hdr, buf, *sgs[2];
      struct virtqueue *vq;
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