Add the rt linux 4.1.3-rt3 as base

Import the rt linux 4.1.3-rt3 as OPNFV kvm base.

It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:

commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date:   Sat Jul 25 12:13:34 2015 +0200

    Prepare v4.1.3-rt3

    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.

Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>

1 files changed, 65 insertions, 0 deletions

diff --git a/kernel/Documentation/IRQ-affinity.txt b/kernel/Documentation/IRQ-affinity.txt
new file mode 100644
index 000000000..01a675175
--- /dev/null
+++ b/kernel/Documentation/IRQ-affinity.txt
@@ -0,0 +1,65 @@
+ChangeLog:
+	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
+(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.