From fbf198030e0b027538c290300cfaf9e2efdce122 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 3 Feb 2016 19:52:23 +0100 Subject: [PATCH] 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 Cc: Rik van Riel Cc: Peter Zijlstra Cc: Frederic Weisbecker Cc: Chris Metcalf Cc: Christoph Lameter Cc: Sebastian Siewior Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1602031948190.25254@nanos Signed-off-by: Thomas Gleixner --- Documentation/kernel-parameters.txt | 9 +++++++++ kernel/irq/irqdesc.c | 21 +++++++++++++++++++-- 2 files changed, 28 insertions(+), 2 deletions(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 551ecf09c8dd..87298f8592b7 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -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: + ,..., + or + - + (must be a positive range in ascending order) + or a mixture + ,...,- + irqfixup [HW] When an interrupt is not handled search all handlers for it. Intended to get systems with badly broken diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c index 0409da0bcc33..0ccd028817d7 100644 --- a/kernel/irq/irqdesc.c +++ b/kernel/irq/irqdesc.c @@ -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) -- 2.20.1