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Revision 71556b9800fff8bf59075d2c1622acc9d99113ef authored by Linus Torvalds on 16 January 2009, 20:40:37 UTC, committed by Linus Torvalds on 16 January 2009, 20:40:37 UTC 
Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6
 
* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6: (23 commits)
  ACPI PCI hotplug: harden against panic regression
  ACPI: rename main.c to sleep.c
  dell-laptop: move to drivers/platform/x86/ from drivers/misc/
  eeepc-laptop: enable Bluetooth ACPI details
  ACPI: fix ACPI_FADT_S4_RTC_WAKE comment
  kprobes: check CONFIG_FREEZER instead of CONFIG_PM
  PM: Fix freezer compilation if PM_SLEEP is unset
  thermal fixup for broken BIOS which has invalid trip points.
  ACPI: EC: Don't trust ECDT tables from ASUS
  ACPI: EC: Limit workaround for ASUS notebooks even more
  ACPI: thinkpad-acpi: bump up version to 0.22
  ACPI: thinkpad-acpi: handle HKEY event 6030
  ACPI: thinkpad-acpi: clean-up fan subdriver quirk
  ACPI: thinkpad-acpi: start the event hunt season
  ACPI: thinkpad-acpi: handle HKEY thermal and battery alarms
  ACPI: thinkpad-acpi: clean up hotkey_notify()
  ACPI: thinkpad-acpi: use killable instead of interruptible mutexes
  ACPI: thinkpad-acpi: add UWB radio support
  ACPI: thinkpad-acpi: preserve radio state across shutdown
  ACPI: thinkpad-acpi: resume with radios disabled
  ...
2 parent s abcea85 + d45e085
Raw File
IRQ-affinity.txt 
ChangeLog:
	Started by Ingo Molnar <mingo@redhat.com>
	Update by Max Krasnyansky <maxk@qualcomm.com>

SMP IRQ affinity

/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.

/proc/irq/default_smp_affinity specifies default affinity mask that applies
to all non-active IRQs. Once IRQ is allocated/activated its affinity bitmask
will be set to the default mask. It can then be changed as described above.
Default mask is 0xffffffff.

Here is an example of restricting IRQ44 (eth1) to CPU0-3 then restricting
it to CPU4-7 (this is an 8-CPU SMP box):

[root@moon 44]# cd /proc/irq/44
[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 'CPU\|44:'
           CPU0       CPU1       CPU2       CPU3      CPU4       CPU5        CPU6       CPU7
 44:       1068       1785       1785       1783         0          0           0         0    IO-APIC-level  eth1

As can be seen from the line above IRQ44 was delivered only to the first four
processors (0-3).
Now lets restrict that IRQ to CPU(4-7).

[root@moon 44]# echo f0 > smp_affinity
[root@moon 44]# cat smp_affinity
000000f0
[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 |  'CPU\|44:'
           CPU0       CPU1       CPU2       CPU3      CPU4       CPU5        CPU6       CPU7
 44:       1068       1785       1785       1783      1784       1069        1070       1069   IO-APIC-level  eth1

This time around IRQ44 was delivered only to the last four processors.
i.e counters for the CPU0-3 did not change.
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