Commit fbf19803 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

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: default avatarThomas 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: default avatarThomas Gleixner <tglx@linutronix.de>
parent c7c42ec2

Documentation/kernel-parameters.txt

+9 −0
Original line number Diff line number Diff line
@@ -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

kernel/irq/irqdesc.c

+19 −2
Original line number Diff line number Diff line
@@ -24,9 +24,26 @@ 
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);

#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

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