[PATCH] MIPS: SGI-IP27: micro-optimize arch_init_irq()

[PATCH] MIPS: SGI-IP27: micro-optimize arch_init_irq()

[Yury Norov]

The function sets adjasted 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, whth
the associate overhead.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
 arch/mips/sgi-ip27/ip27-irq.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/arch/mips/sgi-ip27/ip27-irq.c b/arch/mips/sgi-ip27/ip27-irq.c
index e6ca34cc9853..3c3a4b56ab95 100644
--- a/arch/mips/sgi-ip27/ip27-irq.c
+++ b/arch/mips/sgi-ip27/ip27-irq.c
@@ -279,11 +279,8 @@ void __init arch_init_irq(void)
 	 * Mark these as reserved right away so they won't be used accidentally
 	 * later.
 	 */
-	for (i = 0; i <= CPU_CALL_B_IRQ; i++)
-		set_bit(i, hub_irq_map);
-
-	for (i = NI_BRDCAST_ERR_A; i <= MSC_PANIC_INTR; i++)
-		set_bit(i, hub_irq_map);
+	bitmap_set(hub_irq_map, 0, CPU_CALL_B_IRQ + 1);
+	bitmap_set(hub_irq_map, NI_BRDCAST_ERR_A, MSC_PANIC_INTR - NI_BRDCAST_ERR_A + 1);
 
 	fn = irq_domain_alloc_named_fwnode("HUB");
 	WARN_ON(fn == NULL);
-- 
2.40.1

Re: [PATCH] MIPS: SGI-IP27: micro-optimize arch_init_irq()

[Thomas Bogendoerfer]

On Sat, Apr 13, 2024 at 11:49:13AM -0700, Yury Norov wrote:
> The function sets adjasted 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, whth
> the associate overhead.
> 
> Signed-off-by: Yury Norov <yury.norov@gmail.com>
> ---
>  arch/mips/sgi-ip27/ip27-irq.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/mips/sgi-ip27/ip27-irq.c b/arch/mips/sgi-ip27/ip27-irq.c
> index e6ca34cc9853..3c3a4b56ab95 100644
> --- a/arch/mips/sgi-ip27/ip27-irq.c
> +++ b/arch/mips/sgi-ip27/ip27-irq.c
> @@ -279,11 +279,8 @@ void __init arch_init_irq(void)
>  	 * Mark these as reserved right away so they won't be used accidentally
>  	 * later.
>  	 */
> -	for (i = 0; i <= CPU_CALL_B_IRQ; i++)
> -		set_bit(i, hub_irq_map);
> -
> -	for (i = NI_BRDCAST_ERR_A; i <= MSC_PANIC_INTR; i++)
> -		set_bit(i, hub_irq_map);
> +	bitmap_set(hub_irq_map, 0, CPU_CALL_B_IRQ + 1);
> +	bitmap_set(hub_irq_map, NI_BRDCAST_ERR_A, MSC_PANIC_INTR - NI_BRDCAST_ERR_A + 1);
>  
>  	fn = irq_domain_alloc_named_fwnode("HUB");
>  	WARN_ON(fn == NULL);
> -- 
> 2.40.1

applied to mips-next.

Thomas.

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