As part of fixing another perf issue, observed that after a perf run,
the interrupt got disabled on one/more cores.
| [ARCLinux]# cat /proc/interrupts | grep perf
| 20: 0 0 0 0 ARCv2 core Intc 20 ARC perf counters
|
| [ARCLinux]# perf record -c 20000 /sbin/hackbench
| Running with 10*40 (== 400) tasks.
|
| [ARCLinux]# cat /proc/interrupts | grep perf
| 20: 0 522 8 51916 ARCv2 core Intc 20 ARC perf counters
|
| [ARCLinux]# perf record -c 20000 /sbin/hackbench
| Running with 10*40 (== 400) tasks.
|
| [ARCLinux]# cat /proc/interrupts | grep perf
| 20: 0 522 8 104368 ARCv2 core Intc 20 ARC perf counters
Turns out that despite requesting perf irq as percpu, the flow handler
registered was not handle_percpu_irq()
Given that on ARCv2 cores, IRQs < 24 are always private to cpu, we
register the right handler at the very onset.
Cc: Marc Zyngier <marc.zyng...@arm.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Alexey Brodkin <abrod...@synopsys.com>
Cc: sta...@vger.kernel.org #4.2+
Cc: linux-ker...@vger.kernel.org
Signed-off-by: Vineet Gupta <vgu...@synopsys.com>
---
arch/arc/kernel/intc-arcv2.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/arch/arc/kernel/intc-arcv2.c b/arch/arc/kernel/intc-arcv2.c
index 26c156827479..0394f9f61b46 100644
--- a/arch/arc/kernel/intc-arcv2.c
+++ b/arch/arc/kernel/intc-arcv2.c
@@ -106,10 +106,21 @@ static struct irq_chip arcv2_irq_chip = {
static int arcv2_irq_map(struct irq_domain *d, unsigned int irq,
irq_hw_number_t hw)
{
- if (irq == TIMER0_IRQ || irq == IPI_IRQ)
+ /*
+ * core intc IRQs [16, 23]:
+ * Statically assigned always private-per-core (Timers, WDT, IPI, PCT)
+ */
+ if (hw < 24) {
+ /*
+ * A subsequent request_percpu_irq() fails if percpu_devid is
+ * not set. That in turns sets NOAUTOEN, meaning each core needs
+ * to call enable_percpu_irq()
+ */
+ irq_set_percpu_devid(irq);
irq_set_chip_and_handler(irq, &arcv2_irq_chip,
handle_percpu_irq);
- else
+ } else {
irq_set_chip_and_handler(irq, &arcv2_irq_chip,
handle_level_irq);
+ }
return 0;
}
--
1.9.1
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