linux-kernel - Re: [PATCH v2 1/2] MIPS: SGI-IP27: micro-optimize arch_init

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Message-ID: <Zh+uPB0druail4XC@alpha.franken.de>
Date: Wed, 17 Apr 2024 13:10:52 +0200
From: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To: Yury Norov <yury.norov@...il.com>
Cc: Florian Fainelli <f.fainelli@...il.com>, linux-mips@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] MIPS: SGI-IP27: micro-optimize arch_init_irq()

On Tue, Apr 16, 2024 at 10:37:10AM -0700, Yury Norov wrote:
> The function sets adjusted groups of bits in hub_irq_map by using
> for-loops. There's a bitmap_set() function dedicated to do this.
> 
> Because [0, CPU_CALL_B_IRQ] and [NI_BRDCAST_ERR_A, MSC_PANIC_INTR]
> ranges belong to the same machine word, bitmap_set() would boil down
> to an inline wrapper in both cases, avoiding generating a loop, with
> the associate overhead. Effectively, it would be a compile-time:
> 
> 	*hub_irq_map = GENMASK() | GENMASK();
> 
> Signed-off-by: Yury Norov <yury.norov@...il.com>
> ---
>  arch/mips/sgi-ip27/ip27-irq.c | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/mips/sgi-ip27/ip27-irq.c b/arch/mips/sgi-ip27/ip27-irq.c
> index 8f5299b269e7..d8acdf0439d2 100644
> --- a/arch/mips/sgi-ip27/ip27-irq.c
> +++ b/arch/mips/sgi-ip27/ip27-irq.c
> @@ -277,7 +277,6 @@ void __init arch_init_irq(void)
>  {
>  	struct irq_domain *domain;
>  	struct fwnode_handle *fn;
> -	int i;

I've already applied your first version, so I need an incremental
patch, which just removes the unused variable.

Thomas.

-- 
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