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genirq: Add default affinity mask command line option 

If we isolate CPUs, then we don't want random device interrupts on them. Even
w/o the user space irq balancer enabled we can end up with irqs on non boot
cpus and chasing newly requested interrupts is a tedious task.

Allow to restrict the default irq affinity mask.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1602031948190.25254@nanos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Thomas Gleixner 2016-02-03 19:52:23 +01:00
parent c7c42ec2ba
commit fbf198030e
2 changed files with 28 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
Documentation/kernel-parameters.txt
View File

@ -1687,6 +1687,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
ip= [IP_PNP]
See Documentation/filesystems/nfs/nfsroot.txt.
irqaffinity= [SMP] Set the default irq affinity mask
Format:
<cpu number>,...,<cpu number>
or
<cpu number>-<cpu number>
(must be a positive range in ascending order)
or a mixture
<cpu number>,...,<cpu number>-<cpu number>
irqfixup [HW]
When an interrupt is not handled search all handlers
for it. Intended to get systems with badly broken

21
kernel/irq/irqdesc.c
View File

@ -24,10 +24,27 @@
static struct lock_class_key irq_desc_lock_class;
#if defined(CONFIG_SMP)
static int __init irq_affinity_setup(char *str)
{
zalloc_cpumask_var(&irq_default_affinity, GFP_NOWAIT);
cpulist_parse(str, irq_default_affinity);
/*
* Set at least the boot cpu. We don't want to end up with
* bugreports caused by random comandline masks
*/
cpumask_set_cpu(smp_processor_id(), irq_default_affinity);
return 1;
}
__setup("irqaffinity=", irq_affinity_setup);
static void __init init_irq_default_affinity(void)
{
alloc_cpumask_var(&irq_default_affinity, GFP_NOWAIT);
cpumask_setall(irq_default_affinity);
#ifdef CONFIG_CPUMASK_OFFSTACK
if (!irq_default_affinity)
zalloc_cpumask_var(&irq_default_affinity, GFP_NOWAIT);
#endif
if (cpumask_empty(irq_default_affinity))
cpumask_setall(irq_default_affinity);
}
#else
static void __init init_irq_default_affinity(void)