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| author | Michael S. Tsirkin <mst@redhat.com> | 2019-09-03 03:38:16 -0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2019-09-05 09:53:01 +0200 |
| commit | f4d7c8e3da9173ac7b0498abc3aab0d320efe997 (patch) | |
| tree | faa189cc53c654723d6f0f57ce7c8c598314036f /net/vmw_vsock | |
| parent | 9c895c1bc576f1091a685f62595dc520659863df (diff) | |
| download | linux-f4d7c8e3da9173ac7b0498abc3aab0d320efe997.tar.gz linux-f4d7c8e3da9173ac7b0498abc3aab0d320efe997.tar.bz2 linux-f4d7c8e3da9173ac7b0498abc3aab0d320efe997.zip | |
vsock/virtio: a better comment on credit update
The comment we have is just repeating what the code does.
Include the *reason* for the condition instead.
Cc: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/vmw_vsock')
| -rw-r--r-- | net/vmw_vsock/virtio_transport_common.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c index 94cc0fa3e848..5bb70c692b1e 100644 --- a/net/vmw_vsock/virtio_transport_common.c +++ b/net/vmw_vsock/virtio_transport_common.c @@ -307,8 +307,13 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk, spin_unlock_bh(&vvs->rx_lock); - /* We send a credit update only when the space available seen - * by the transmitter is less than VIRTIO_VSOCK_MAX_PKT_BUF_SIZE + /* To reduce the number of credit update messages, + * don't update credits as long as lots of space is available. + * Note: the limit chosen here is arbitrary. Setting the limit + * too high causes extra messages. Too low causes transmitter + * stalls. As stalls are in theory more expensive than extra + * messages, we set the limit to a high value. TODO: experiment + * with different values. */ if (free_space < VIRTIO_VSOCK_MAX_PKT_BUF_SIZE) { virtio_transport_send_credit_update(vsk, |