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IRQ-affinity.txt: standardize document format 

Each text file under Documentation follows a different
format. Some doesn't even have titles!

Change its representation to follow the adopted standard,
using ReST markups for it to be parseable by Sphinx:

- Add a title for the document;
- mark literal blocks as such;
- use a bulleted list for changelog.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This commit is contained in:
Mauro Carvalho Chehab 2017-05-14 15:22:54 -03:00 committed by Jonathan Corbet
parent f5981a5c59
commit ae2f26aa4c
1 changed files with 41 additions and 36 deletions
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77
Documentation/IRQ-affinity.txt
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@ -1,8 +1,11 @@
ChangeLog: ================
Started by Ingo Molnar <mingo@redhat.com>
Update by Max Krasnyansky <maxk@qualcomm.com>
SMP IRQ affinity SMP IRQ affinity
================
ChangeLog:
- Started by Ingo Molnar <mingo@redhat.com>
- Update by Max Krasnyansky <maxk@qualcomm.com>
/proc/irq/IRQ#/smp_affinity and /proc/irq/IRQ#/smp_affinity_list specify /proc/irq/IRQ#/smp_affinity and /proc/irq/IRQ#/smp_affinity_list specify
which target CPUs are permitted for a given IRQ source. It's a bitmask which target CPUs are permitted for a given IRQ source. It's a bitmask
@ -16,50 +19,52 @@ will be set to the default mask. It can then be changed as described above.
Default mask is 0xffffffff. Default mask is 0xffffffff.
Here is an example of restricting IRQ44 (eth1) to CPU0-3 then restricting Here is an example of restricting IRQ44 (eth1) to CPU0-3 then restricting
it to CPU4-7 (this is an 8-CPU SMP box): it to CPU4-7 (this is an 8-CPU SMP box)::
[root@moon 44]# cd /proc/irq/44 [root@moon 44]# cd /proc/irq/44
[root@moon 44]# cat smp_affinity [root@moon 44]# cat smp_affinity
ffffffff ffffffff
[root@moon 44]# echo 0f > smp_affinity [root@moon 44]# echo 0f > smp_affinity
[root@moon 44]# cat smp_affinity [root@moon 44]# cat smp_affinity
0000000f 0000000f
[root@moon 44]# ping -f h [root@moon 44]# ping -f h
PING hell (195.4.7.3): 56 data bytes PING hell (195.4.7.3): 56 data bytes
... ...
--- hell ping statistics --- --- hell ping statistics ---
6029 packets transmitted, 6027 packets received, 0% packet loss 6029 packets transmitted, 6027 packets received, 0% packet loss
round-trip min/avg/max = 0.1/0.1/0.4 ms round-trip min/avg/max = 0.1/0.1/0.4 ms
[root@moon 44]# cat /proc/interrupts | grep 'CPU\|44:' [root@moon 44]# cat /proc/interrupts | grep 'CPU\|44:'
CPU0 CPU1 CPU2 CPU3 CPU4 CPU5 CPU6 CPU7 CPU0 CPU1 CPU2 CPU3 CPU4 CPU5 CPU6 CPU7
44: 1068 1785 1785 1783 0 0 0 0 IO-APIC-level eth1 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 As can be seen from the line above IRQ44 was delivered only to the first four
processors (0-3). processors (0-3).
Now lets restrict that IRQ to CPU(4-7). 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]# echo f0 > smp_affinity
[root@moon 44]# ping -f h [root@moon 44]# cat smp_affinity
PING hell (195.4.7.3): 56 data bytes 000000f0
.. [root@moon 44]# ping -f h
--- hell ping statistics --- PING hell (195.4.7.3): 56 data bytes
2779 packets transmitted, 2777 packets received, 0% packet loss ..
round-trip min/avg/max = 0.1/0.5/585.4 ms --- hell ping statistics ---
[root@moon 44]# cat /proc/interrupts | 'CPU\|44:' 2779 packets transmitted, 2777 packets received, 0% packet loss
CPU0 CPU1 CPU2 CPU3 CPU4 CPU5 CPU6 CPU7 round-trip min/avg/max = 0.1/0.5/585.4 ms
44: 1068 1785 1785 1783 1784 1069 1070 1069 IO-APIC-level eth1 [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. This time around IRQ44 was delivered only to the last four processors.
i.e counters for the CPU0-3 did not change. i.e counters for the CPU0-3 did not change.
Here is an example of limiting that same irq (44) to cpus 1024 to 1031: Here is an example of limiting that same irq (44) to cpus 1024 to 1031::
[root@moon 44]# echo 1024-1031 > smp_affinity_list [root@moon 44]# echo 1024-1031 > smp_affinity_list
[root@moon 44]# cat smp_affinity_list [root@moon 44]# cat smp_affinity_list
1024-1031 1024-1031
Note that to do this with a bitmask would require 32 bitmasks of zero Note that to do this with a bitmask would require 32 bitmasks of zero
to follow the pertinent one. to follow the pertinent one.