-
Stop and disable irqbalance
.
# service irqbalance stop
# chkconfig irqbalance off
-
Disable Message Signal Interrupts (MSI). For RHEL4, this will have to be disabled at the driver level. For RHEL5, you can disable it at the driver level, or at the kernel level. Setting pci-nomsi
in grub.conf
is supported for disabling at the kernel level in RHEL5.
To disable it at a driver level, see the driver-specific documentation. For an example, to disable it for the bnx2
driver, use this syntax in /etc/modprobe.conf
:
options bnx2 disable_msi=1
-
Find the IRQ of the device in question. For this example, we want to set the smp_affinity
parameter for eth3
.
# egrep "CPU|eth3"
CPU0 CPU1 CPU2 CPU3 CPU4 PU5 PU6 CPU7
177: 3 8 7 6 2 4 2 5 IO-APIC-level eth3
From the preceding output, the first column shows an IRQ of 177
for eth3
.
-
Set the smp_affinity
setting in hex numbers for the CPUs that you want to handle the interrupts for this device. Here is a chart for eight CPUs and their hex values.
CPU BIN HEX
0 0000 0001 1
1 0000 0010 2
2 0000 0100 4
3 0000 1000 8
4 0001 0000 10
5 0010 0000 20
6 0100 0000 40
7 1000 0000 80
If we want only CPUs 3
and 5
to handle the interrupts from eth3
, we would add hex 8 + hex 20 and get hex 28.
-
Put the value 28
hex into smp_affinity
for eth3
, IRQ 177
.
# /bin/echo "28" > /proc/irq/177/smp_affinity
Put this echo command in /etc/rc.local
, or some other startup file.
