Re: [PATCH] genirq: Add default affinity mask command line option

On 12 November 2012 22:27, Punit Agrawal punit.agrawal@arm.com wrote:

I am attaching a patch by Thomas Gleixner which adds a kernel command line parameter to set the defauilt IRQ affinity mask. Could you please integrate this in your tree for the next Linaro release?

I've been using this patch for sometime now and it doesn't introduce any regressions. There is a possibility that this patch will make it upstream via the RT patches in the near future but in the meanwhile, we'd like to carry this patch as well.

Hi Punit,

I agree with you that many of us would be interested in using this patch, but i am not sure about which tree should it land into?

@Andrey/Tixy: Any other better tree you can suggest for carrying this one? Or is my tree the best place :)

From 52a7d44f58a262e166575abc57aa0bd3bfc8cfbb Mon Sep 17 00:00:00 2001 From: Thomas Gleixner tglx@linutronix.de Date: Fri, 25 May 2012 16:59:47 +0200 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.

Allow to restrict the default irq affinity mask.

Signed-off-by: Thomas Gleixner tglx@linutronix.de

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 7d82468..00fedab 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1164,6 +1164,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted. See comment before ip2_setup() in drivers/char/ip2/ip2base.c.

•   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
  

diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c index 192a302..473b2b6 100644 --- a/kernel/irq/irqdesc.c +++ b/kernel/irq/irqdesc.c @@ -23,10 +23,27 @@ 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) -- 1.7.9.5