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Message-ID: <1437552576.2783.19.camel@googlemail.com>
Date: Wed, 22 Jul 2015 10:09:36 +0200
From: Sebastian Poehn <sebastian.poehn@...il.com>
To: netdev@...r.kernel.org
Subject: [PATCH] Documentation: Mention chunk format for irq affinity
It may not be obvious for everyone that bitmasks in proc require
32bit chunking
Signed-off-by: Sebastian Poehn <sebastian.poehn@...il.com>
---
Documentation/IRQ-affinity.txt | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/Documentation/IRQ-affinity.txt b/Documentation/IRQ-affinity.txt
index 01a6751..d873dab 100644
--- a/Documentation/IRQ-affinity.txt
+++ b/Documentation/IRQ-affinity.txt
@@ -55,6 +55,11 @@ 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.
+Note that you have to split the bitmask to chunks when using more that 32 cpus:
+[root@...n 44]# echo 80,00000000 > smp_affinity
+[root@...n 44]# cat smp_affinity
+80,00000000
+
Here is an example of limiting that same irq (44) to cpus 1024 to 1031:
[root@...n 44]# echo 1024-1031 > smp_affinity_list
--
2.4.3
--
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