From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DB5B7361DA8 for ; Wed, 1 Apr 2026 21:51:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775080303; cv=none; b=DAIPrqJ5cuVk55GvRdbaJQbbY3dX0o6ZoukVs65K4UjTssBF2WU5JgQ9pw7PZSrj1GfWrIJhgXN19wRQ3cCafiEMZ/CiByg0pKfkaTtk94Ao9fp34gx0Y64ZmmFLp4vPRmLtfd00q3m0jHhLATm2rcxxe8T2I6nWijdc4bHO9Q4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775080303; c=relaxed/simple; bh=j6PbRjiLaQdCvtyVSkhYVLngtowrzIKmmBuSNvRo4GU=; h=Date:Message-ID:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=VxAw/wpHxwbwftUCPtyJJ2HdNx2ypr8F/kk5zyDLRQivfEfATdLdiBkx6xxUDxWuqQLNR3nZLeECMzzD6dPDABfAtuBWNU4zxWGyC2d6t5odoDRAqMVv1L6tOt1LWDaeGb9BAEIG4X6qML/DlG3abmO+/4jrCnTwq6QVjcnPj1w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KnDPDiDs; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="KnDPDiDs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AEBD9C116C6; Wed, 1 Apr 2026 21:51:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775080303; bh=j6PbRjiLaQdCvtyVSkhYVLngtowrzIKmmBuSNvRo4GU=; h=Date:From:To:Cc:Subject:References:From; b=KnDPDiDsr2CuR3yxecUmLHC2jw7EJLdvzyKq3/vMdMeCnuZkmnzvonRvwi5AqPSYe BVx104vN9QIaXP67xZgojVAFdsn+iXu3aVtuZIX+ZvvFjcUOziZTQY1eHfj8ZgMQV0 32scj5zalg+QPGKO8ApNTHpURpT8Y6/OH1X2v08URS2gHHSklBMlMVFZb4FbuqQzTx ZS7B5Wi4k3cAyIAa04it8UyMcZGX1IBh25rVKX5F8ovxeZ+Ayvk5+OtH9rtzZddWfr j/Awm4F2nljJWnf8DrCdzuyZO4BhLFRH/88dciC2bTVJg6inRrF8R3xg7MnGeiFTc4 ZLmy+EavxpRNQ== Date: Wed, 01 Apr 2026 23:51:39 +0200 Message-ID: <20260401201348.140519102@kernel.org> User-Agent: quilt/0.68 From: Thomas Gleixner To: LKML Cc: x86@kernel.org, Michael Kelley , Dmitry Ilvokhin , Radu Rendec , Jan Kiszka , Kieran Bingham , Florian Fainelli , Marc Zyngier Subject: [patch V5 02/15] genirq/proc: Avoid formatting zero counts in /proc/interrupts References: <20260401195625.213446764@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 From: Thomas Gleixner A large portion of interrupt count entries are zero. There is no point in formatting the zero value as it is way cheeper to just emit a constant string. Collect the number of consecutive zero counts and emit them in one go before a non-zero count and at the end of the line. Signed-off-by: Thomas Gleixner Reviewed-by: Dmitry Ilvokhin Reviewed-by: Radu Rendec --- V2: Use sizeof() for ZSTR1_LEN - Dmitry --- include/linux/interrupt.h | 1 + kernel/irq/proc.c | 42 +++++++++++++++++++++++++++++++++++++----- 2 files changed, 38 insertions(+), 5 deletions(-) --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -864,6 +864,7 @@ static inline void init_irq_proc(void) struct seq_file; int show_interrupts(struct seq_file *p, void *v); int arch_show_interrupts(struct seq_file *p, int prec); +void irq_proc_emit_counts(struct seq_file *p, unsigned int __percpu *cnts); extern int early_irq_init(void); extern int arch_probe_nr_irqs(void); --- a/kernel/irq/proc.c +++ b/kernel/irq/proc.c @@ -450,6 +450,42 @@ int __weak arch_show_interrupts(struct s # define ACTUAL_NR_IRQS irq_get_nr_irqs() #endif +#define ZSTR1 " 0" +#define ZSTR1_LEN (sizeof(ZSTR1) - 1) +#define ZSTR16 ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 \ + ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 +#define ZSTR256 ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 \ + ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 + +static inline void irq_proc_emit_zero_counts(struct seq_file *p, unsigned int zeros) +{ + if (!zeros) + return; + + for (unsigned int n = min(zeros, 256); n; zeros -= n, n = min(zeros, 256)) + seq_write(p, ZSTR256, n * ZSTR1_LEN); +} + +static inline unsigned int irq_proc_emit_count(struct seq_file *p, unsigned int cnt, + unsigned int zeros) +{ + if (!cnt) + return zeros + 1; + + irq_proc_emit_zero_counts(p, zeros); + seq_put_decimal_ull_width(p, " ", cnt, 10); + return 0; +} + +void irq_proc_emit_counts(struct seq_file *p, unsigned int __percpu *cnts) +{ + unsigned int cpu, zeros = 0; + + for_each_online_cpu(cpu) + zeros = irq_proc_emit_count(p, per_cpu(*cnts, cpu), zeros); + irq_proc_emit_zero_counts(p, zeros); +} + int show_interrupts(struct seq_file *p, void *v) { const unsigned int nr_irqs = irq_get_nr_irqs(); @@ -485,11 +521,7 @@ int show_interrupts(struct seq_file *p, return 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); - } + irq_proc_emit_counts(p, &desc->kstat_irqs->cnt); seq_putc(p, ' '); guard(raw_spinlock_irq)(&desc->lock);