sh/irq: use seq_put_decimal_ull_width() for decimal values

[PATCH v2] sh/irq: use seq_put_decimal_ull_width() for decimal values

Posted by David Wang 1 year, 2 months ago

On a system with n CPUs and m interrupts, there will be n*m decimal
values yielded via seq_printf(.."%10u "..) which has significant costs
parsing format string and is less efficient than
seq_put_decimal_ull_width(). Stress reading /proc/interrupts
indicates ~30% performance improvement with this patch.

Signed-off-by: David Wang <00107082@163.com>
---
 arch/sh/kernel/irq.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/sh/kernel/irq.c b/arch/sh/kernel/irq.c
index 4e6835de54cf..9022d8af9d68 100644
--- a/arch/sh/kernel/irq.c
+++ b/arch/sh/kernel/irq.c
@@ -43,9 +43,9 @@ int arch_show_interrupts(struct seq_file *p, int prec)
 {
 	int j;
 
-	seq_printf(p, "%*s: ", prec, "NMI");
+	seq_printf(p, "%*s:", prec, "NMI");
 	for_each_online_cpu(j)
-		seq_printf(p, "%10u ", per_cpu(irq_stat.__nmi_count, j));
+		seq_put_decimal_ull_width(p, " ", per_cpu(irq_stat.__nmi_count, j), 10);
 	seq_printf(p, "  Non-maskable interrupts\n");
 
 	seq_printf(p, "%*s: %10u\n", prec, "ERR", atomic_read(&irq_err_count));
-- 
2.39.2

Re: [PATCH v2] sh/irq: use seq_put_decimal_ull_width() for decimal values

Posted by John Paul Adrian Glaubitz 1 year ago

Hi David,

On Sat, 2024-11-30 at 21:49 +0800, David Wang wrote:
> On a system with n CPUs and m interrupts, there will be n*m decimal
> values yielded via seq_printf(.."%10u "..) which has significant costs
> parsing format string and is less efficient than
> seq_put_decimal_ull_width(). Stress reading /proc/interrupts
> indicates ~30% performance improvement with this patch.
> 
> Signed-off-by: David Wang <00107082@163.com>
> ---
>  arch/sh/kernel/irq.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/sh/kernel/irq.c b/arch/sh/kernel/irq.c
> index 4e6835de54cf..9022d8af9d68 100644
> --- a/arch/sh/kernel/irq.c
> +++ b/arch/sh/kernel/irq.c
> @@ -43,9 +43,9 @@ int arch_show_interrupts(struct seq_file *p, int prec)
>  {
>  	int j;
>  
> -	seq_printf(p, "%*s: ", prec, "NMI");
> +	seq_printf(p, "%*s:", prec, "NMI");
>  	for_each_online_cpu(j)
> -		seq_printf(p, "%10u ", per_cpu(irq_stat.__nmi_count, j));
> +		seq_put_decimal_ull_width(p, " ", per_cpu(irq_stat.__nmi_count, j), 10);
>  	seq_printf(p, "  Non-maskable interrupts\n");
>  
>  	seq_printf(p, "%*s: %10u\n", prec, "ERR", atomic_read(&irq_err_count));

Reviewed-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>

Thanks,
Adrian

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