From bd49fea7586b9d39a38846e9ef4ac056e4eb6e59 Mon Sep 17 00:00:00 2001 From: Shachar Raindel Date: Fri, 12 Mar 2021 15:45:27 -0800 Subject: hv_netvsc: Add a comment clarifying batching logic The batching logic in netvsc_send is non-trivial, due to a combination of the Linux API and the underlying hypervisor interface. Add a comment explaining why the code is written this way. Signed-off-by: Shachar Raindel Signed-off-by: Haiyang Zhang Reviewed-by: Dexuan Cui Signed-off-by: David S. Miller --- .../device_drivers/ethernet/microsoft/netvsc.rst | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) (limited to 'Documentation/networking/device_drivers') diff --git a/Documentation/networking/device_drivers/ethernet/microsoft/netvsc.rst b/Documentation/networking/device_drivers/ethernet/microsoft/netvsc.rst index c3f51c672a68..fc5acd427a5d 100644 --- a/Documentation/networking/device_drivers/ethernet/microsoft/netvsc.rst +++ b/Documentation/networking/device_drivers/ethernet/microsoft/netvsc.rst @@ -87,11 +87,15 @@ Receive Buffer contain one or more packets. The number of receive sections may be changed via ethtool Rx ring parameters. - There is a similar send buffer which is used to aggregate packets for sending. - The send area is broken into chunks of 6144 bytes, each of section may - contain one or more packets. The send buffer is an optimization, the driver - will use slower method to handle very large packets or if the send buffer - area is exhausted. + There is a similar send buffer which is used to aggregate packets + for sending. The send area is broken into chunks, typically of 6144 + bytes, each of section may contain one or more packets. Small + packets are usually transmitted via copy to the send buffer. However, + if the buffer is temporarily exhausted, or the packet to be transmitted is + an LSO packet, the driver will provide the host with pointers to the data + from the SKB. This attempts to achieve a balance between the overhead of + data copy and the impact of remapping VM memory to be accessible by the + host. XDP support ----------- -- cgit