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From: Anup Patel <anup@brainfault.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>,
	Jason Cooper <jason@lakedaemon.net>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Palmer Dabbelt <palmer@sifive.com>,
	"linux-kernel@vger.kernel.org List"
	<linux-kernel@vger.kernel.org>, Atish Patra <atish.patra@wdc.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-riscv@lists.infradead.org
Subject: Re: [PATCH v4 2/5] irqchip: sifive-plic: Don't inline plic_toggle() and plic_irq_toggle()
Date: Sat, 19 Jan 2019 10:30:52 +0530	[thread overview]
Message-ID: <CAAhSdy1JOFW3f_xtZSjjHPzcHWoG5C50tXzm7U=Oav9GYD=j8g@mail.gmail.com> (raw)
In-Reply-To: <20190115155437.GA13095@infradead.org>

On Tue, Jan 15, 2019 at 9:24 PM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Thu, Dec 27, 2018 at 04:48:18PM +0530, Anup Patel wrote:
> > The plic_toggle() uses raw_spin_lock() and plic_irq_toggle has a
> > for loop so both these functions are not suitable for being inline
> > hence this patch removes the inline keyword.
>
> That is a weird argument for a function which has by design exactly
> two callers and is in the hot path.  The alternative to the inline
> here would be to duplicate the code.

It's strange that you see it as weird argument. Both plic_toggle()
and plic_irq_toggle() are 5+ lines functions with loops. The loop
is clear in plic_irq_toggle() whereas raw_spin_lock() in plic_toggle()
expands into inline-assembly spin-loop because raw_spin_lock()
is a macro (not function).

Further looking at disassembly of both functions, these are 55+
instructions. I think we let GCC decide whether these functions
should be inlined or not rather than us explicitly making these
functions inline.

Regards,
Anup

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  reply	other threads:[~2019-01-19  5:01 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-27 11:18 [PATCH v4 0/5] IRQ affinity support in PLIC driver Anup Patel
2018-12-27 11:18 ` [PATCH v4 1/5] irqchip: sifive-plic: Pre-compute context hart base and enable base Anup Patel
2018-12-27 11:18 ` [PATCH v4 2/5] irqchip: sifive-plic: Don't inline plic_toggle() and plic_irq_toggle() Anup Patel
2019-01-15 15:54   ` Christoph Hellwig
2019-01-19  5:00     ` Anup Patel [this message]
2018-12-27 11:18 ` [PATCH v4 3/5] irqchip: sifive-plic: Add warning in plic_init() if handler already present Anup Patel
2019-01-15 15:54   ` Christoph Hellwig
2019-01-19  5:03     ` Anup Patel
2018-12-27 11:18 ` [PATCH v4 4/5] irqchip: sifive-plic: Differentiate between PLIC handler and context Anup Patel
2019-01-15 15:56   ` Christoph Hellwig
2019-01-19  5:25     ` Anup Patel
2018-12-27 11:18 ` [PATCH v4 5/5] irqchip: sifive-plic: Implement irq_set_affinity() for SMP host Anup Patel
2019-01-15 15:57   ` Christoph Hellwig
2019-01-19  5:26     ` Anup Patel
2019-01-08 12:14 ` [PATCH v4 0/5] IRQ affinity support in PLIC driver Anup Patel
2019-01-23 18:57   ` Palmer Dabbelt

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