From: Julien Thierry <julien.thierry@arm.com>
To: Shijith Thotton <sthotton@marvell.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Cc: Ganapatrao Kulkarni <gkulkarni@marvell.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Jan Glauber <jglauber@marvell.com>,
Will Deacon <will.deacon@arm.com>,
Robert Richter <rrichter@marvell.com>,
Jayachandran Chandrasekharan Nair <jnair@marvell.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] genirq: update irq stats from NMI handlers
Date: Thu, 4 Jul 2019 08:13:51 +0100 [thread overview]
Message-ID: <6adfb296-50f1-9efb-0840-cc8732b8ebf9@arm.com> (raw)
In-Reply-To: <1562214115-14022-1-git-send-email-sthotton@marvell.com>
Hi Shijith,
On 04/07/2019 05:22, Shijith Thotton wrote:
> The NMI handlers handle_percpu_devid_fasteoi_nmi() and
> handle_fasteoi_nmi() added by commit 2dcf1fbcad35 ("genirq: Provide NMI
> handlers") do not update the interrupt counts. Due to that the NMI
> interrupt count does not show up correctly in /proc/interrupts.
>
> Update the functions to fix this. With this change, we can see stats of
> the perf NMI interrupts on arm64.
>
> Fixes: 2dcf1fbcad35 ("genirq: Provide NMI handlers")
>
> Signed-off-by: Shijith Thotton <sthotton@marvell.com>
> ---
> kernel/irq/chip.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
> index 29d6c7d070b4..88d1e054c6ea 100644
> --- a/kernel/irq/chip.c
> +++ b/kernel/irq/chip.c
> @@ -748,6 +748,8 @@ void handle_fasteoi_nmi(struct irq_desc *desc)
> unsigned int irq = irq_desc_get_irq(desc);
> irqreturn_t res;
>
> + kstat_incr_irqs_this_cpu(desc);
> +
This needs to be called with the desc lock taken, otherwise we're likely
to corrupt desc->tot_count.
But taking the desc lock is something we can't do in NMI context (
*spin_lock_irq*() won't prevent an NMI from happening).
> trace_irq_handler_entry(irq, action);
> /*
> * NMIs cannot be shared, there is only one action.
> @@ -962,6 +964,8 @@ void handle_percpu_devid_fasteoi_nmi(struct irq_desc *desc)
> unsigned int irq = irq_desc_get_irq(desc);
> irqreturn_t res;
>
> + __kstat_incr_irqs_this_cpu(desc);
> +
Looking at handle_percpu_irq(), I think this might be acceptable. But
does it make sense to only have kstats for percpu NMIs?
Cheers,
--
Julien Thierry
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next prev parent reply other threads:[~2019-07-04 7:14 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-04 4:22 [PATCH] genirq: update irq stats from NMI handlers Shijith Thotton
2019-07-04 7:13 ` Julien Thierry [this message]
2019-07-04 10:36 ` Shijith Thotton
2019-07-04 16:19 ` Thomas Gleixner
2019-07-04 16:31 ` Shijith Thotton
2019-07-05 7:56 ` [PATCH v2] " Shijith Thotton
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