linux-kernel - Re: [PATCH 12/13] riscv/irq: use seq_put_decimal_ull

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Message-ID: <70e006c0.4333.195405bb2e1.Coremail.00107082@163.com>
Date: Wed, 26 Feb 2025 11:45:06 +0800 (CST)
From: "David Wang" <00107082@....com>
To: "Alexandre Ghiti" <alex@...ti.fr>
Cc: paul.walmsley@...ive.com, palmer@...belt.com, aou@...s.berkeley.edu,
	linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org
Subject: Re: [PATCH 12/13] riscv/irq: use seq_put_decimal_ull_width() for
 decimal values

Hi, 

Thanks for the test and  review, and sorry for not giving  more attentions to alignment issues when made the patch.
But if alignment should not be changed, simply appending a [space] is not enough:  the patch change
'%10u[space]" to "[space]%10u",   one [space] is moved from tail to the front,  and to restore to its original state
, one [space] should be removed from front.  and It would make the code  ugly and unpleasant  to remove a [space]
from this line 
        seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i, prec >= 4 ? " " : "");
( or make changes to seq_put_decimal_ull_width)


Kind of think that it does not worth the effort if  code changes are way too unpleasant....


Thanks
David
 

At 2025-02-25 23:10:26, "Alexandre Ghiti" <alex@...ti.fr> wrote:
>Hi David,
>
>On 08/11/2024 17:25, David Wang wrote:
>> Performance improvement for reading /proc/interrupts on arch riscv
>>
>> Signed-off-by: David Wang <00107082@....com>
>> ---
>>   arch/riscv/kernel/smp.c | 3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
>> index c180a647a30e..f1e9c3db094c 100644
>> --- a/arch/riscv/kernel/smp.c
>> +++ b/arch/riscv/kernel/smp.c
>> @@ -226,7 +226,8 @@ void show_ipi_stats(struct seq_file *p, int prec)
>>   		seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i,
>>   			   prec >= 4 ? " " : "");
>>   		for_each_online_cpu(cpu)
>> -			seq_printf(p, "%10u ", irq_desc_kstat_cpu(ipi_desc[i], cpu));
>> +			seq_put_decimal_ull_width(p, " ",
>> +						  irq_desc_kstat_cpu(ipi_desc[i], cpu), 10);
>>   		seq_printf(p, " %s\n", ipi_names[i]);
>>   	}
>>   }
>
>
>Very late answer sorry!
>
>I don't have the same output before and after your patch because 
>seq_put_decimal_ull_width() second argument is placed *before* the 
>number, not after as it was before.
>
>The following diff fixes the issue:
>
>diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c index 
>f1e9c3db094c3..4b80ee4e5b2c0 100644 --- a/arch/riscv/kernel/smp.c +++ 
>b/arch/riscv/kernel/smp.c @@ -225,9 +225,11 @@ void 
>show_ipi_stats(struct seq_file *p, int prec) for (i = 0; i < IPI_MAX; 
>i++) { seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i, prec >= 4 ? " " : 
>""); - for_each_online_cpu(cpu) - seq_put_decimal_ull_width(p, " ", + 
>for_each_online_cpu(cpu) { + seq_put_decimal_ull_width(p, NULL, 
>irq_desc_kstat_cpu(ipi_desc[i], cpu), 10); + seq_putc(p, ' '); + } 
>seq_printf(p, " %s\n", ipi_names[i]); } }
>
>Will you respin a new version?
>
>Thanks,
>
>Alex