diff options
| author | Mauro Carvalho Chehab <mchehab+huawei@kernel.org> | 2020-05-01 17:37:51 +0200 |
|---|---|---|
| committer | Jonathan Corbet <corbet@lwn.net> | 2020-05-15 12:00:56 -0600 |
| commit | e00b0ab86c79c4e82eb821ac6d6a3daef2e3e600 (patch) | |
| tree | b4ff4930b099762724de349e73b85fe1ff731691 /Documentation/IRQ-affinity.txt | |
| parent | a74e2a226452ea75d26b1f83860bff91a11da1ac (diff) | |
docs: add IRQ documentation at the core-api book
There are 4 IRQ documentation files under Documentation/*.txt.
Move them into a new directory (core-api/irq) and add a new
index file for it.
While here, use a title markup for the Debugging section of the
irq-domain.rst file.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/2da7485c3718e1442e6b4c2dd66857b776e8899b.1588345503.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Diffstat (limited to 'Documentation/IRQ-affinity.txt')
| -rw-r--r-- | Documentation/IRQ-affinity.txt | 70 |
1 files changed, 0 insertions, 70 deletions
diff --git a/Documentation/IRQ-affinity.txt b/Documentation/IRQ-affinity.txt deleted file mode 100644 index 29da5000836a..000000000000 --- a/Documentation/IRQ-affinity.txt +++ /dev/null @@ -1,70 +0,0 @@ -================ -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 -which target CPUs are permitted for a given IRQ source. It's a bitmask -(smp_affinity) or cpu list (smp_affinity_list) 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 of all cpus. - -/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. - -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 - -Note that to do this with a bitmask would require 32 bitmasks of zero -to follow the pertinent one. |