From: Marc Zyngier <maz@kernel.org>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Sumit Garg <sumit.garg@linaro.org>,
Android Kernel Team <kernel-team@android.com>,
Florian Fainelli <f.fainelli@gmail.com>,
Russell King <linux@arm.linux.org.uk>,
Jason Cooper <jason@lakedaemon.net>,
Saravana Kannan <saravanak@google.com>,
Andrew Lunn <andrew@lunn.ch>,
Catalin Marinas <catalin.marinas@arm.com>,
Gregory Clement <gregory.clement@bootlin.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <will@kernel.org>,
Valentin Schneider <Valentin.Schneider@arm.com>,
LAK <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v3 03/16] arm64: Allow IPIs to be handled as normal interrupts
Date: Mon, 19 Oct 2020 14:04:19 +0100 [thread overview]
Message-ID: <353f13b0dcc6c7ea1b44012d9632a0cc@kernel.org> (raw)
In-Reply-To: <CAKfTPtDjPpri5Gt6kLeFp_B_zJUZ5DYXEqtJ+0VKohU-y9bFEQ@mail.gmail.com>
Hi Vincent,
On 2020-10-19 13:42, Vincent Guittot wrote:
> Hi Marc,
>
> On Tue, 1 Sep 2020 at 16:44, Marc Zyngier <maz@kernel.org> wrote:
>>
>> In order to deal with IPIs as normal interrupts, let's add
>> a new way to register them with the architecture code.
>>
>> set_smp_ipi_range() takes a range of interrupts, and allows
>> the arch code to request them as if the were normal interrupts.
>> A standard handler is then called by the core IRQ code to deal
>> with the IPI.
>>
>> This means that we don't need to call irq_enter/irq_exit, and
>> that we don't need to deal with set_irq_regs either. So let's
>> move the dispatcher into its own function, and leave handle_IPI()
>> as a compatibility function.
>>
>> On the sending side, let's make use of ipi_send_mask, which
>> already exists for this purpose.
>>
>> One of the major difference is that we end up, in some cases
>> (such as when performing IRQ time accounting on the scheduler
>> IPI), end up with nested irq_enter()/irq_exit() pairs.
>> Other than the (relatively small) overhead, there should be
>> no consequences to it (these pairs are designed to nest
>> correctly, and the accounting shouldn't be off).
>
> While rebasing on mainline, I have faced a performance regression for
> the benchmark:
> perf bench sched pipe
> on my arm64 dual quad core (hikey) and my 2 nodes x 112 CPUS (thx2)
>
> The regression comes from:
> commit: d3afc7f12987 ("arm64: Allow IPIs to be handled as normal
> interrupts")
That's interesting, as this patch doesn't really change anything (most
of the potential overhead comes in later). The only potential overhead
I can see is that the scheduler_ipi() call is now wrapped around
irq_enter()/irq_exit().
>
> v5.9 + this patch
> hikey : 48818(+/- 0.31) 37503(+/- 0.15%) -23.2%
> thx2 : 132410(+/- 1.72) 122646(+/- 1.92%) -7.4%
>
> By + this patch, I mean merging branch from this patch. Whereas
> merging the previous:
> commit: 83cfac95c018 ("genirq: Allow interrupts to be excluded from
> /proc/interrupts")
> It doesn't show any regression
Since you are running perf, can you spot where the overhead occurs?
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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next prev parent reply other threads:[~2020-10-19 13:05 UTC|newest]
Thread overview: 84+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-01 14:43 [PATCH v3 00/16] arm/arm64: Turning IPIs into normal interrupts Marc Zyngier
2020-09-01 14:43 ` [PATCH v3 01/16] genirq: Add fasteoi IPI flow Marc Zyngier
2020-09-01 14:43 ` [PATCH v3 02/16] genirq: Allow interrupts to be excluded from /proc/interrupts Marc Zyngier
2020-09-01 14:43 ` [PATCH v3 03/16] arm64: Allow IPIs to be handled as normal interrupts Marc Zyngier
2020-09-11 15:05 ` Catalin Marinas
2020-10-19 12:42 ` Vincent Guittot
2020-10-19 13:04 ` Marc Zyngier [this message]
2020-10-19 15:43 ` Vincent Guittot
2020-10-19 16:00 ` Valentin Schneider
2020-10-27 10:12 ` Vincent Guittot
2020-10-27 10:37 ` Marc Zyngier
2020-10-27 10:50 ` Vincent Guittot
2020-10-27 11:21 ` Vincent Guittot
2020-10-27 12:06 ` Marc Zyngier
2020-10-27 13:17 ` Vincent Guittot
[not found] ` <c66367b0-e8a0-2b7b-13c3-c9413462357c@huawei.com>
2021-05-06 11:44 ` Marc Zyngier
2021-05-07 7:30 ` He Ying
2021-05-07 8:56 ` Marc Zyngier
2021-05-07 9:31 ` He Ying
2020-09-01 14:43 ` [PATCH v3 04/16] ARM: " Marc Zyngier
2020-09-01 14:43 ` [PATCH v3 05/16] irqchip/gic-v3: Describe the SGI range Marc Zyngier
2020-09-01 14:43 ` [PATCH v3 06/16] irqchip/gic-v3: Configure SGIs as standard interrupts Marc Zyngier
2020-09-01 14:43 ` [PATCH v3 07/16] irqchip/gic: Refactor SMP configuration Marc Zyngier
2020-09-01 14:43 ` [PATCH v3 08/16] irqchip/gic: Configure SGIs as standard interrupts Marc Zyngier
[not found] ` <CGME20200914130601eucas1p23ce276d168dee37909b22c75499e68da@eucas1p2.samsung.com>
2020-09-14 13:06 ` Marek Szyprowski
2020-09-14 13:13 ` Marc Zyngier
2020-09-14 13:26 ` Marek Szyprowski
2020-09-14 15:09 ` Marc Zyngier
2020-09-15 6:48 ` Marek Szyprowski
2020-09-15 8:07 ` Marc Zyngier
2020-09-15 8:35 ` Marek Szyprowski
2020-09-15 9:48 ` Marc Zyngier
2020-09-16 14:16 ` Jon Hunter
2020-09-16 15:10 ` Marc Zyngier
2020-09-16 15:46 ` Jon Hunter
2020-09-16 15:55 ` Marc Zyngier
2020-09-16 15:58 ` Jon Hunter
2020-09-16 16:22 ` Marc Zyngier
2020-09-16 16:28 ` Marc Zyngier
2020-09-16 19:08 ` Jon Hunter
2020-09-16 19:06 ` Jon Hunter
2020-09-16 19:26 ` Mikko Perttunen
2020-09-16 19:39 ` Jon Hunter
2020-09-17 7:40 ` Linus Walleij
2020-09-17 7:50 ` Marc Zyngier
2020-09-17 7:54 ` Jon Hunter
2020-09-17 8:45 ` Marc Zyngier
2020-09-17 8:49 ` Jon Hunter
2020-09-17 8:54 ` Marek Szyprowski
2020-09-17 9:09 ` Jon Hunter
2020-09-17 9:13 ` Marek Szyprowski
2020-09-17 9:29 ` Marc Zyngier
2020-09-17 14:53 ` Jon Hunter
2020-09-17 18:24 ` Jon Hunter
2020-09-18 8:24 ` Marc Zyngier
2020-09-17 8:56 ` Marc Zyngier
2020-09-17 10:11 ` Linus Walleij
2020-09-16 14:03 ` Linus Walleij
2020-09-16 14:14 ` Marc Zyngier
2020-09-18 9:58 ` James Morse
2020-09-18 10:21 ` Marc Zyngier
2020-09-01 14:43 ` [PATCH v3 09/16] irqchip/gic-common: Don't enable SGIs by default Marc Zyngier
2020-09-01 14:43 ` [PATCH v3 10/16] irqchip/bcm2836: Configure mailbox interrupts as standard interrupts Marc Zyngier
[not found] ` <CGME20200914143236eucas1p17e8849c67d01db2c5ebb3b6a126aebf4@eucas1p1.samsung.com>
2020-09-14 14:32 ` Marek Szyprowski
2020-09-14 16:10 ` Marc Zyngier
2020-09-14 19:13 ` Marek Szyprowski
2020-09-01 14:43 ` [PATCH v3 11/16] irqchip/hip04: Configure IPIs " Marc Zyngier
2020-09-01 14:43 ` [PATCH v3 12/16] irqchip/armada-370-xp: " Marc Zyngier
2020-09-01 14:43 ` [PATCH v3 13/16] arm64: Kill __smp_cross_call and co Marc Zyngier
2020-09-11 15:06 ` Catalin Marinas
2020-09-01 14:43 ` [PATCH v3 14/16] arm64: Remove custom IRQ stat accounting Marc Zyngier
2020-09-11 15:06 ` Catalin Marinas
2020-09-01 14:43 ` [PATCH v3 15/16] ARM: Kill __smp_cross_call and co Marc Zyngier
2020-09-01 14:43 ` [PATCH v3 16/16] ARM: Remove custom IRQ stat accounting Marc Zyngier
2020-09-02 7:41 ` kernel test robot
2020-09-02 20:20 ` Marc Zyngier
2020-09-24 9:00 ` Guillaume Tucker
2020-09-24 9:29 ` Marc Zyngier
2020-09-24 13:09 ` Guillaume Tucker
2020-09-28 9:00 ` Guillaume Tucker
2020-09-24 13:34 ` Fabio Estevam
2020-09-24 14:19 ` Guillaume Tucker
2020-09-07 6:06 ` [PATCH v3 00/16] arm/arm64: Turning IPIs into normal interrupts hasegawa-hitomi
2020-09-16 16:54 ` Florian Fainelli
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