Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/Documentation/IRQ-affinity.txt
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
File MIME type: text/plain
File size: 1362 byte(s)
Tag kernel26-2.6.12-alx-r9
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 |