man/man4/wm.4

.\"	$NetBSD: wm.4,v 1.44 2024/05/01 11:22:06 andvar Exp $
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.\" Written by Jason R. Thorpe for Wasabi Systems, Inc.
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.Dd February 17, 2021
.Dt WM 4
.Os
.Sh NAME
.Nm wm
.Nd Intel i8254x Gigabit Ethernet driver
.Sh SYNOPSIS
.Cd "wm* at pci? dev ? function ?"
.Pp
.Cd options WM_RX_PROCESS_LIMIT_DEFAULT
.Cd options WM_RX_INTR_PROCESS_LIMIT_DEFAULT
.Pp
Configuration of PHYs may also be necessary.
See
.Xr mii 4 .
.Sh DESCRIPTION
The
.Nm
device driver supports Gigabit Ethernet interfaces based on the Intel
i8254x family of Gigabit Ethernet chips.
The interfaces supported by the
.Nm
driver include:
.Bl -bullet
.It
Intel i82542 1000BASE-X Ethernet
.It
Intel i82543GC 1000BASE-X Ethernet
.It
Intel i82543GC 1000BASE-T Ethernet
.It
Intel i82544EI 1000BASE-T Ethernet
.It
Intel i82544EI 1000BASE-X Ethernet
.It
Intel i82544GC 1000BASE-T Ethernet
.It
Intel i82544GC (LOM) 1000BASE-T Ethernet
.It
Intel i82540EM 1000BASE-T Ethernet
.It
Intel i82540EM (LOM) 1000BASE-T Ethernet
.It
Intel i82540EP 1000BASE-T Ethernet
.It
Intel i82541EI 1000BASE-T Ethernet
.It
Intel i82541EI (Mobile) 1000BASE-T Ethernet
.It
Intel i82541ER 1000BASE-T Ethernet
.It
Intel i82541GI 1000BASE-T Ethernet
.It
Intel i82541PI 1000BASE-T Ethernet
.It
Intel i82545EM 1000BASE-T Ethernet
.It
Intel i82545EM 1000BASE-X Ethernet
.It
Intel i82545GB 1000BASE-T Ethernet
.It
Intel i82545GB 1000BASE-X Ethernet
.It
Intel i82545GM 1000BASE-T Ethernet
.It
Intel i82546EB 1000BASE-T Ethernet
.Pq dual-port
.It
Intel i82546EB 1000BASE-X Ethernet
.Pq dual-port
.It
Intel i82546GB 1000BASE-T Ethernet
.Pq dual-port
.It
Intel i82546GB 1000BASE-X Ethernet
.Pq dual-port
.It
Intel i82547EI 1000BASE-T Ethernet
.Pq CSA
.It
Intel i82547GI 1000BASE-T Ethernet
.Pq CSA
.It
Intel i82571 1000BASE-T Ethernet
.Pq dual-port
.It
Intel i82572 1000BASE-T Ethernet
.It
Intel i82573 1000BASE-T Ethernet
.It
Intel i82575 1000BASE-T Ethernet
.It
Intel i82576 Ethernet (Copper, Fiber)
.It
Intel i80003 Ethernet (Copper, Fiber)
.It
Intel i82801H (ICH8 LAN) 1000BASE-T Ethernet
.It
Intel i82801I (ICH9 LAN) 1000BASE-T Ethernet
.It
Intel i82801J (ICH10 LAN) 1000BASE-T Ethernet
.It
Intel 82578 with Intel 5 series chipset (PCH)
.It
Intel 82579 with Intel 6 or 7 series chipset (PCH2)
.It
Intel 82580 Ethernet (Copper, Fiber)
.It
Intel 82583 1000BASE-T Ethernet
.It
Intel I350 Ethernet (Copper, Fiber)
.It
Intel I354 (C2000 Internal) Ethernet (Copper, Fiber)
.It
Intel I210 Ethernet (Copper, Fiber)
.It
Intel I211 Ethernet
.It
Intel I217 and I218 Ethernet
.It
Intel I219 Ethernet (with Intel [123]00 series chipset)
.El
.Pp
In addition to Intel's own
.Dq PRO/1000
line of Gigabit Ethernet interfaces, these chips also appear on
some server systems, processor evaluation boards, and in embedded
systems.
.Pp
The i825[478]x supports IPv4/TCP/UDP checksumming and TCP segmentation
in hardware.
The
.Nm
driver supports these features of the chip.
At least for some chips (e.g. I219) hardware TCP segmentation is slow,
and slows down transmit performance when turned on.
See
.Xr ifconfig 8
for information on how to enable this feature.
.Pp
Many chips supported by the
.Nm
driver support jumbo frames, however several chips do not support
jumbo frames, e.g. i82542, i82081H and 82567V.
Jumbo frames can be configured via the interface MTU setting.
Selecting an MTU larger than 1500 bytes with the
.Xr ifconfig 8
utility configures the adapter to receive and transmit jumbo frames.
.\" .Sh DIAGNOSTICS
.\" XXX to be done.
.Sh OPTIONS
The driver default behavior is to handle packets in interrupt context,
which reduces the CPU time available to user processes when under
heavy network load. The
.Em hw.wmX.txrx_workqueue
.Xr sysctl 8
alters this behavior so that packets are handled by a kernel thread,
which executes at a lower priority. This gives user processes more
opportunity to be executed, at the expense of network throughput.
.Pp
The following options can be set at build time:
.Bl -tag -width WM_RX_INTR_PROCESS_LIMIT_DEFAULT -offset 3n
.It Dv WM_RX_PROCESS_LIMIT_DEFAULT
The maximum number of received packets processed in each
.Xr softint 9
context.
This option only affects multiqueue.
The value range is from zero to
.Dv UINT_MAX .
The default value is 100.
When you increase this value, both the receive latency and
the receive throughput will increase.
.It Dv WM_TX_PROCESS_LIMIT_DEFAULT
Transmit side of
.Dv WM_RX_PROCESS_LIMIT_DEFAULT .
.It Dv WM_RX_INTR_PROCESS_LIMIT_DEFAULT
The maximum number of received packets processed in each
hardware interrupt context.
This option only affects multiqueue.
The value range is from zero to
.Dv UINT_MAX .
The default value is 0.
When you increase this value, both the receive latency and
the receive throughput will decrease.
.It Dv WM_TX_INTR_PROCESS_LIMIT_DEFAULT
Transmit side of
.Dv WM_RX_INTR_PROCESS_LIMIT_DEFAULT .
.It Dv WM_EVENT_COUNTERS
Enable many event counters such as each Tx drop counter and Rx interrupt
counter.
In 64 bit architectures, this is enabled by default.
Caution: If this flag is enabled, the number of evcnt entries increase
very much.
.It Dv WM_DISABLE_EVENT_COUNTERS
Disable event counters for 64 bit architectures.
.It Dv WM_DISABLE_MSI
If this option is set non-zero value, this driver does not use msi.
The default value is 0.
.It Dv WM_DISABLE_MSIX
If this option is set non-zero value, this driver does not use msix.
The default value is 0.
.El
.Pp
Setting
.Dv WM_RX_INTR_PROCESS_LIMIT_DEFAULT
to zero means so-called polling mode, that is, once an interrupt occurs,
the driver keep processing received packets until
.Dv WM_RX_PROCESS_LIMIT_DEFAULT .
Polling mode increases latency a little, however it suppresses
performance degradation at high load very well.
.Pp
If you want to disable polling mode (to use traditional interrupt
driven mode), you should set
.Dv WM_RX_PROCESS_LIMIT_DEFAULT
to zero and set
.Dv WM_RX_INTR_PROCESS_LIMIT_DEFAULT
to
.Dv UINT_MAX .
.Sh SEE ALSO
.Xr arp 4 ,
.Xr ifmedia 4 ,
.Xr mii 4 ,
.Xr netintro 4 ,
.Xr pci 4 ,
.Xr ifconfig 8 ,
.Xr sysctl 8
.Sh HISTORY
The
.Nm
driver first appeared in
.Nx 1.6 .
.Sh AUTHORS
The
.Nm
driver was written by
.An Jason R. Thorpe Aq Mt thorpej@wasabisystems.com .
.Sh BUGS
EEE (Energy Efficiency Ethernet) is not currently supported.