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authorIngo Molnar <mingo@elte.hu>2008-07-15 23:12:58 +0200
committerIngo Molnar <mingo@elte.hu>2008-07-15 23:12:58 +0200
commit1e09481365ce248dbb4eb06dad70129bb5807037 (patch)
treec0cff5bef95c8b5e7486f144718ade9a06c284dc /Documentation/filesystems/proc.txt
parent3e2f69fdd1b00166e7d589bce56b2d36a9e74374 (diff)
parentb9d2252c1e44fa83a4e65fdc9eb93db6297c55af (diff)
downloadblackbird-op-linux-1e09481365ce248dbb4eb06dad70129bb5807037.tar.gz
blackbird-op-linux-1e09481365ce248dbb4eb06dad70129bb5807037.zip
Merge branch 'linus' into core/softlockup
Conflicts: kernel/softlockup.c Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'Documentation/filesystems/proc.txt')
-rw-r--r--Documentation/filesystems/proc.txt29
1 files changed, 18 insertions, 11 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index dbc3c6a3650f..7f268f327d75 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -380,28 +380,35 @@ i386 and x86_64 platforms support the new IRQ vector displays.
Of some interest is the introduction of the /proc/irq directory to 2.4.
It could be used to set IRQ to CPU affinity, this means that you can "hook" an
IRQ to only one CPU, or to exclude a CPU of handling IRQs. The contents of the
-irq subdir is one subdir for each IRQ, and one file; prof_cpu_mask
+irq subdir is one subdir for each IRQ, and two files; default_smp_affinity and
+prof_cpu_mask.
For example
> ls /proc/irq/
0 10 12 14 16 18 2 4 6 8 prof_cpu_mask
- 1 11 13 15 17 19 3 5 7 9
+ 1 11 13 15 17 19 3 5 7 9 default_smp_affinity
> ls /proc/irq/0/
smp_affinity
-The contents of the prof_cpu_mask file and each smp_affinity file for each IRQ
-is the same by default:
+smp_affinity is a bitmask, in which you can specify which CPUs can handle the
+IRQ, you can set it by doing:
- > cat /proc/irq/0/smp_affinity
- ffffffff
+ > echo 1 > /proc/irq/10/smp_affinity
+
+This means that only the first CPU will handle the IRQ, but you can also echo
+5 which means that only the first and fourth CPU can handle the IRQ.
-It's a bitmask, in which you can specify which CPUs can handle the IRQ, you can
-set it by doing:
+The contents of each smp_affinity file is the same by default:
+
+ > cat /proc/irq/0/smp_affinity
+ ffffffff
- > echo 1 > /proc/irq/prof_cpu_mask
+The default_smp_affinity mask applies to all non-active IRQs, which are the
+IRQs which have not yet been allocated/activated, and hence which lack a
+/proc/irq/[0-9]* directory.
-This means that only the first CPU will handle the IRQ, but you can also echo 5
-which means that only the first and fourth CPU can handle the IRQ.
+prof_cpu_mask specifies which CPUs are to be profiled by the system wide
+profiler. Default value is ffffffff (all cpus).
The way IRQs are routed is handled by the IO-APIC, and it's Round Robin
between all the CPUs which are allowed to handle it. As usual the kernel has
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