From: Stephen Hemminger <stephen@networkplumber•org>
To: kys@microsoft•com, haiyangz@microsoft•com,
sthemmin@microsoft•com, corbet@lwn•net
Cc: devel@linuxdriverproject•org, netdev@vger•kernel.org,
linux-doc@vger•kernel.org
Subject: [PATCH net-next v3 2/3] netvsc: add documentation
Date: Tue, 1 Aug 2017 19:58:54 -0700 [thread overview]
Message-ID: <20170802025855.11521-3-sthemmin@microsoft.com> (raw)
In-Reply-To: <20170802025855.11521-1-sthemmin@microsoft.com>
Add some background documentation on netvsc device options
and limitations.
Signed-off-by: Stephen Hemminger <sthemmin@microsoft•com>
---
Documentation/networking/netvsc.txt | 63 +++++++++++++++++++++++++++++++++++++
MAINTAINERS | 1 +
2 files changed, 64 insertions(+)
create mode 100644 Documentation/networking/netvsc.txt
diff --git a/Documentation/networking/netvsc.txt b/Documentation/networking/netvsc.txt
new file mode 100644
index 000000000000..4ddb4e4b0426
--- /dev/null
+++ b/Documentation/networking/netvsc.txt
@@ -0,0 +1,63 @@
+Hyper-V network driver
+======================
+
+Compatibility
+=============
+
+This driver is compatible with Windows Server 2012 R2, 2016 and
+Windows 10.
+
+Features
+========
+
+ Checksum offload
+ ----------------
+ The netvsc driver supports checksum offload as long as the
+ Hyper-V host version does. Windows Server 2016 and Azure
+ support checksum offload for TCP and UDP for both IPv4 and
+ IPv6. Windows Server 2012 only supports checksum offload for TCP.
+
+ Receive Side Scaling
+ --------------------
+ Hyper-V supports receive side scaling. For TCP, packets are
+ distributed among available queues based on IP address and port
+ number. Current versions of Hyper-V host, only distribute UDP
+ packets based on the IP source and destination address.
+ The port number is not used as part of the hash value for UDP.
+ Fragmented IP packets are not distributed between queues;
+ all fragmented packets arrive on the first channel.
+
+ Generic Receive Offload, aka GRO
+ --------------------------------
+ The driver supports GRO and it is enabled by default. GRO coalesces
+ like packets and significantly reduces CPU usage under heavy Rx
+ load.
+
+ SR-IOV support
+ --------------
+ Hyper-V supports SR-IOV as a hardware acceleration option. If SR-IOV
+ is enabled in both the vSwitch and the guest configuration, then the
+ Virtual Function (VF) device is passed to the guest as a PCI
+ device. In this case, both a synthetic (netvsc) and VF device are
+ visible in the guest OS and both NIC's have the same MAC address.
+
+ The VF is enslaved by netvsc device. The netvsc driver will transparently
+ switch the data path to the VF when it is available and up.
+ Network state (addresses, firewall, etc) should be applied only to the
+ netvsc device; the slave device should not be accessed directly in
+ most cases. The exceptions are if some special queue discipline or
+ flow direction is desired, these should be applied directly to the
+ VF slave device.
+
+ Receive Buffer
+ --------------
+ Packets are received into a receive area which is created when device
+ is probed. The receive area is broken into MTU sized chunks and each may
+ 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.
diff --git a/MAINTAINERS b/MAINTAINERS
index 207e45310620..448f2f67802f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6258,6 +6258,7 @@ M: Haiyang Zhang <haiyangz@microsoft•com>
M: Stephen Hemminger <sthemmin@microsoft•com>
L: devel@linuxdriverproject•org
S: Maintained
+F: Documentation/networking/netvsc.txt
F: arch/x86/include/asm/mshyperv.h
F: arch/x86/include/uapi/asm/hyperv.h
F: arch/x86/kernel/cpu/mshyperv.c
--
2.11.0
next prev parent reply other threads:[~2017-08-02 2:58 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-02 2:58 [PATCH net-next v3 0/3] netvsc: transparent VF support Stephen Hemminger
2017-08-02 2:58 ` [PATCH net-next v3 1/3] netvsc: transparent VF management Stephen Hemminger
2017-08-03 14:19 ` Olaf Hering
2017-08-02 2:58 ` Stephen Hemminger [this message]
2017-08-02 2:58 ` [PATCH net-next v3 3/3] netvsc: remove bonding setup script Stephen Hemminger
2017-08-02 23:55 ` [PATCH net-next v3 0/3] netvsc: transparent VF support David Miller
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