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Message-Id: <1452902191-26419-1-git-send-email-kamal@canonical.com>
Date: Fri, 15 Jan 2016 15:56:31 -0800
From: Kamal Mostafa <kamal@...onical.com>
To: Vineet Gupta <vgupta@...opsys.com>
Cc: Marc Zyngier <marc.zyngier@....com>,
Thomas Gleixner <tglx@...utronix.de>,
Peter Zijlstra <peterz@...radead.org>,
Alexey Brodkin <abrodkin@...opsys.com>,
linux-kernel@...r.kernel.org, Kamal Mostafa <kamal@...onical.com>,
kernel-team@...ts.ubuntu.com
Subject: [4.2.y-ckt stable] Patch "ARCv2: intc: Fix random perf irq disabling in SMP setup" has been added to the 4.2.y-ckt tree
This is a note to let you know that I have just added a patch titled
ARCv2: intc: Fix random perf irq disabling in SMP setup
to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree
which can be found at:
http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue
This patch is scheduled to be released in version 4.2.8-ckt2.
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Kamal
---8<------------------------------------------------------------
>From 749f09fb7217b21c0f46c133ba10e6b55032095b Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@...opsys.com>
Date: Fri, 11 Dec 2015 15:54:03 +0530
Subject: ARCv2: intc: Fix random perf irq disabling in SMP setup
commit 8eb0984bf4fe82237f95481ff0afe514a676c717 upstream.
As part of fixing another perf issue, observed that after a perf run,
the interrupt got disabled on one/more cores.
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.
Before Fix
| [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
After Fix
| [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: 64198 62012 62697 67803 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: 126014 122792 123301 133654 ARCv2 core Intc 20 ARC perf counters
Cc: Marc Zyngier <marc.zyngier@....com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Alexey Brodkin <abrodkin@...opsys.com>
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Vineet Gupta <vgupta@...opsys.com>
Signed-off-by: Kamal Mostafa <kamal@...onical.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 26c1568..0394f9f 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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