diff options
| author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
| commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
| tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/IRQ-affinity.txt | |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'Documentation/IRQ-affinity.txt')
| -rw-r--r-- | Documentation/IRQ-affinity.txt | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/Documentation/IRQ-affinity.txt b/Documentation/IRQ-affinity.txt new file mode 100644 index 000000000000..938d7dd05490 --- /dev/null +++ b/Documentation/IRQ-affinity.txt @@ -0,0 +1,37 @@ + +SMP IRQ affinity, started by Ingo Molnar <mingo@redhat.com> + + +/proc/irq/IRQ#/smp_affinity specifies which target CPUs are permitted +for a given IRQ source. It's a bitmask of allowed CPUs. It's not allowed +to turn off all CPUs, and if an IRQ controller does not support IRQ +affinity then the value will not change from the default 0xffffffff. + +Here is an example of restricting IRQ44 (eth1) to CPU0-3 then restricting +the IRQ to CPU4-7 (this is an 8-CPU SMP box): + +[root@moon 44]# cat smp_affinity +ffffffff +[root@moon 44]# echo 0f > smp_affinity +[root@moon 44]# cat smp_affinity +0000000f +[root@moon 44]# ping -f h +PING hell (195.4.7.3): 56 data bytes +... +--- hell ping statistics --- +6029 packets transmitted, 6027 packets received, 0% packet loss +round-trip min/avg/max = 0.1/0.1/0.4 ms +[root@moon 44]# cat /proc/interrupts | grep 44: + 44: 0 1785 1785 1783 1783 1 +1 0 IO-APIC-level eth1 +[root@moon 44]# echo f0 > smp_affinity +[root@moon 44]# ping -f h +PING hell (195.4.7.3): 56 data bytes +.. +--- hell ping statistics --- +2779 packets transmitted, 2777 packets received, 0% packet loss +round-trip min/avg/max = 0.1/0.5/585.4 ms +[root@moon 44]# cat /proc/interrupts | grep 44: + 44: 1068 1785 1785 1784 1784 1069 1070 1069 IO-APIC-level eth1 +[root@moon 44]# + |