K 10
svn:author
V 3
jdp
K 8
svn:date
V 27
2003-08-01T17:33:59.000000Z
K 7
svn:log
V 954
Add facilities for tuning the "em" driver's interrupt delays without
recompiling the driver.  See the comments near the top of "if_em.h"
for descriptions of these delays.  Four new loader tunables control
the system-wide default values:

    hw.em.tx_int_delay
    hw.em.rx_int_delay
    hw.em.tx_abs_int_delay
    hw.em.rx_abs_int_delay

The tunables are specified in microseconds.  The valid range is
0-67108 usec., and 0 means that the timer is disabled.

There are also four new sysctls (actually, a set of four for each
"em" device in the system) to query and change the interrupt delays
after the system is up:

    hw.em0.tx_int_delay
    hw.em0.rx_int_delay
    hw.em0.tx_abs_int_delay (not present for 82542/3/4 adapters)
    hw.em0.rx_abs_int_delay (not present for 82542/3/4 adapters)

It seems to be OK to change these values even while the adapter is
passing traffic.

Approved by:	Prafulla Deuskar <pdeuskar@FreeBSD.ORG>
MFC after:	4 weeks

END