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genirq: Introduce effective affinity mask

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There is currently no way to evaluate the effective affinity mask of a
given interrupt. Many irq chips allow only a single target CPU or a subset
of CPUs in the affinity mask.

Updating the mask at the time of setting the affinity to the subset would
be counterproductive because information for cpu hotplug about assigned
interrupt affinities gets lost. On CPU hotplug it's also pointless to force
migrate an interrupt, which is not targeted at the CPU effectively. But
currently the information is not available.

Provide a seperate mask to be updated by the irq_chip->irq_set_affinity()
implementations. Implement the read only proc files so the user can see the
effective mask as well w/o trying to deduce it from /proc/interrupts.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Link: http://lkml.kernel.org/r/20170619235446.247834245@linutronix.de
This commit is contained in:
Thomas Gleixner
2017-06-20 01:37:38 +02:00
parent c1a8038696
commit 0d3f54257d
5 changed files with 134 additions and 7 deletions
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4
kernel/irq/debugfs.c
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@@ -36,6 +36,10 @@ static void irq_debug_show_masks(struct seq_file *m, struct irq_desc *desc)
msk = irq_data_get_affinity_mask(data);
seq_printf(m, "affinity: %*pbl\n", cpumask_pr_args(msk));
#ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK
msk = irq_data_get_effective_affinity_mask(data);
seq_printf(m, "effectiv: %*pbl\n", cpumask_pr_args(msk));
#endif
#ifdef CONFIG_GENERIC_PENDING_IRQ
msk = desc->pending_mask;
seq_printf(m, "pending: %*pbl\n", cpumask_pr_args(msk));