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authorLinus Torvalds <torvalds@linux-foundation.org>2017-07-15 22:58:58 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-07-15 22:58:58 +0300
commit486088bc4689f826b80aa317b45ac9e42e8b25ee (patch)
treeadf5847a6119d24da990d9e336f005c4a316e6be /Documentation/IRQ-affinity.txt
parent52f6c588c77b76d548201470c2a28263a41b462b (diff)
parent43e5f7e1fa66531777c49791014c3124ea9208d8 (diff)
downloadlinux-486088bc4689f826b80aa317b45ac9e42e8b25ee.tar.xz
Merge tag 'standardize-docs' of git://git.lwn.net/linux
Pull documentation format standardization from Jonathan Corbet: "This series converts a number of top-level documents to the RST format without incorporating them into the Sphinx tree. The hope is to bring some uniformity to kernel documentation and, perhaps more importantly, have our existing docs serve as an example of the desired formatting for those that will be added later. Mauro has gone through and fixed up a lot of top-level documentation files to make them conform to the RST format, but without moving or renaming them in any way. This will help when we incorporate the ones we want to keep into the Sphinx doctree, but the real purpose is to bring a bit of uniformity to our documentation and let the top-level docs serve as examples for those writing new ones" * tag 'standardize-docs' of git://git.lwn.net/linux: (84 commits) docs: kprobes.txt: Fix whitespacing tee.txt: standardize document format cgroup-v2.txt: standardize document format dell_rbu.txt: standardize document format zorro.txt: standardize document format xz.txt: standardize document format xillybus.txt: standardize document format vfio.txt: standardize document format vfio-mediated-device.txt: standardize document format unaligned-memory-access.txt: standardize document format this_cpu_ops.txt: standardize document format svga.txt: standardize document format static-keys.txt: standardize document format smsc_ece1099.txt: standardize document format SM501.txt: standardize document format siphash.txt: standardize document format sgi-ioc4.txt: standardize document format SAK.txt: standardize document format rpmsg.txt: standardize document format robust-futexes.txt: standardize document format ...
Diffstat (limited to 'Documentation/IRQ-affinity.txt')
-rw-r--r--Documentation/IRQ-affinity.txt75
1 files changed, 40 insertions, 35 deletions
diff --git a/Documentation/IRQ-affinity.txt b/Documentation/IRQ-affinity.txt
index 01a675175a36..29da5000836a 100644
--- a/Documentation/IRQ-affinity.txt
+++ b/Documentation/IRQ-affinity.txt
@@ -1,8 +1,11 @@
+================
+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
@@ -16,50 +19,52 @@ 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
-ffffffff
+ [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
+ [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
+::
+
+ [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.
-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
-1024-1031
+ [root@moon 44]# echo 1024-1031 > smp_affinity_list
+ [root@moon 44]# cat smp_affinity_list
+ 1024-1031
Note that to do this with a bitmask would require 32 bitmasks of zero
to follow the pertinent one.