From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 16 Apr 2005 15:20:36 -0700 Subject: Linux-2.6.12-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! --- Documentation/IRQ-affinity.txt | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) create mode 100644 Documentation/IRQ-affinity.txt (limited to 'Documentation/IRQ-affinity.txt') 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 + + +/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]# + -- cgit v1.2.3-59-g8ed1b