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Commit ae2f26aa authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab Committed by Jonathan Corbet
Browse files

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: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent f5981a5c

Documentation/IRQ-affinity.txt

+40 −35
Original line number Diff line number Diff line 
================

SMP IRQ affinity

================



ChangeLog:

	Started by Ingo Molnar <mingo@redhat.com>

	Update by Max Krasnyansky <maxk@qualcomm.com>

	- Started by Ingo Molnar <mingo@redhat.com>

	- Update by Max Krasnyansky <maxk@qualcomm.com>



SMP IRQ affinity



/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
@@ -16,7 +19,7 @@ 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):

it to CPU4-7 (this is an 8-CPU SMP box)::



	[root@moon 44]# cd /proc/irq/44

	[root@moon 44]# cat smp_affinity
@@ -39,6 +42,8 @@ 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
@@ -55,7 +60,7 @@ round-trip min/avg/max = 0.1/0.5/585.4 ms 
This time around IRQ44 was delivered only to the last four processors.

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]# cat smp_affinity_list