linux-kernel - [tip: irq/core] genirq/proc: Use seq_put_decimal_ull

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Message-ID: <173151627402.32228.16251188627102840898.tip-bot2@tip-bot2>
Date: Wed, 13 Nov 2024 16:44:34 -0000
From: "tip-bot2 for David Wang" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: David Wang <00107082@....com>, Thomas Gleixner <tglx@...utronix.de>,
 x86@...nel.org, linux-kernel@...r.kernel.org, maz@...nel.org
Subject: [tip: irq/core] genirq/proc: Use seq_put_decimal_ull_width() for
 decimal values

The following commit has been merged into the irq/core branch of tip:

Commit-ID:     f9ed1f7c2e26fcd19781774e310a6236d7525c11
Gitweb:        https://git.kernel.org/tip/f9ed1f7c2e26fcd19781774e310a6236d7525c11
Author:        David Wang <00107082@....com>
AuthorDate:    Sat, 09 Nov 2024 00:07:17 +08:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Wed, 13 Nov 2024 17:36:35 +01:00

genirq/proc: Use seq_put_decimal_ull_width() for decimal values

seq_printf() is more expensive than seq_put_decimal_ull_width() due to the
format string parsing costs.

Profiling on a x86 8-core system indicates seq_printf() takes ~47% samples
of show_interrupts(). Replacing it with seq_put_decimal_ull_width() yields
almost 30% performance gain.

[ tglx: Massaged changelog and fixed up coding style ]

Signed-off-by: David Wang <00107082@....com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Link: https://lore.kernel.org/all/20241108160717.9547-1-00107082@163.com

---
 kernel/irq/proc.c |  9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index d226282..f36c33b 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -495,9 +495,12 @@ int show_interrupts(struct seq_file *p, void *v)
 	if (!desc->action || irq_desc_is_chained(desc) || !desc->kstat_irqs)
 		goto outsparse;
 
-	seq_printf(p, "%*d: ", prec, i);
-	for_each_online_cpu(j)
-		seq_printf(p, "%10u ", desc->kstat_irqs ? per_cpu(desc->kstat_irqs->cnt, j) : 0);
+	seq_printf(p, "%*d:", prec, i);
+	for_each_online_cpu(j) {
+		unsigned int cnt = desc->kstat_irqs ? per_cpu(desc->kstat_irqs->cnt, j) : 0;
+
+		seq_put_decimal_ull_width(p, " ", cnt, 10);
+	}
 
 	raw_spin_lock_irqsave(&desc->lock, flags);
 	if (desc->irq_data.chip) {