Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | |
2 | SMP IRQ affinity, started by Ingo Molnar <mingo@redhat.com> | |
3 | ||
4 | ||
5 | /proc/irq/IRQ#/smp_affinity specifies which target CPUs are permitted | |
6 | for a given IRQ source. It's a bitmask of allowed CPUs. It's not allowed | |
7 | to turn off all CPUs, and if an IRQ controller does not support IRQ | |
8 | affinity then the value will not change from the default 0xffffffff. | |
9 | ||
10 | Here is an example of restricting IRQ44 (eth1) to CPU0-3 then restricting | |
11 | the IRQ to CPU4-7 (this is an 8-CPU SMP box): | |
12 | ||
13 | [root@moon 44]# cat smp_affinity | |
14 | ffffffff | |
15 | [root@moon 44]# echo 0f > smp_affinity | |
16 | [root@moon 44]# cat smp_affinity | |
17 | 0000000f | |
18 | [root@moon 44]# ping -f h | |
19 | PING hell (195.4.7.3): 56 data bytes | |
20 | ... | |
21 | --- hell ping statistics --- | |
22 | 6029 packets transmitted, 6027 packets received, 0% packet loss | |
23 | round-trip min/avg/max = 0.1/0.1/0.4 ms | |
24 | [root@moon 44]# cat /proc/interrupts | grep 44: | |
25 | 44: 0 1785 1785 1783 1783 1 | |
26 | 1 0 IO-APIC-level eth1 | |
27 | [root@moon 44]# echo f0 > smp_affinity | |
28 | [root@moon 44]# ping -f h | |
29 | PING hell (195.4.7.3): 56 data bytes | |
30 | .. | |
31 | --- hell ping statistics --- | |
32 | 2779 packets transmitted, 2777 packets received, 0% packet loss | |
33 | round-trip min/avg/max = 0.1/0.5/585.4 ms | |
34 | [root@moon 44]# cat /proc/interrupts | grep 44: | |
35 | 44: 1068 1785 1785 1784 1784 1069 1070 1069 IO-APIC-level eth1 | |
36 | [root@moon 44]# | |
37 |