WM(4) | Device Drivers Manual | WM(4) |
wm
—
wm* at pci? dev ? function ?
options WM_RX_PROCESS_LIMIT_DEFAULT
options WM_RX_INTR_PROCESS_LIMIT_DEFAULT
Configuration of PHYs may also be necessary. See mii(4).
wm
device driver supports Gigabit Ethernet
interfaces based on the Intel i8254x family of Gigabit Ethernet chips. The
interfaces supported by the wm
driver include:
In addition to Intel's own “PRO/1000” line of Gigabit Ethernet interfaces, these chips also appear on some server systems, processor evaluation boards, and in embedded systems.
The i825[478]x supports IPv4/TCP/UDP checksumming and TCP
segmentation in hardware. The wm
driver supports
these features of the chip. See
ifconfig(8) for information
on how to enable this feature.
Many chips supported by the wm
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
ifconfig(8) utility
configures the adapter to receive and transmit jumbo frames.
WM_RX_PROCESS_LIMIT_DEFAULT
UINT_MAX
. The default value is 100. When you
increase this value, both the receive latency and the receive throughput
will increase.WM_TX_PROCESS_LIMIT_DEFAULT
WM_RX_PROCESS_LIMIT_DEFAULT
.WM_RX_INTR_PROCESS_LIMIT_DEFAULT
UINT_MAX
. The default value is 0.
When you increase this value, both the receive latency and the receive
throughput will decrease.WM_TX_INTR_PROCESS_LIMIT_DEFAULT
WM_RX_INTR_PROCESS_LIMIT_DEFAULT
.WM_EVENT_COUNTERS
WM_DISABLE_EVENT_COUNTERS
WM_DISABLE_MSI
WM_DISABLE_MSIX
Setting 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
WM_RX_PROCESS_LIMIT_DEFAULT
. Polling mode increases
latency a little, however it suppresses performance degradation at high load
very well.
If you want to disable polling mode (to use traditional interrupt
driven mode), you should set
WM_RX_PROCESS_LIMIT_DEFAULT
to zero and set
WM_RX_INTR_PROCESS_LIMIT_DEFAULT
to
UINT_MAX
.
wm
driver first appeared in NetBSD
1.6.
wm
driver was written by Jason R.
Thorpe
<thorpej@wasabisystems.com>.
February 17, 2021 | NetBSD 9.4 |