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 170AE366567 for ; Fri, 20 Mar 2026 13:21:38 +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=1774012899; cv=none; b=nbypG8PemFzsXl7mHX2ekhEnlaKswL/sm5NtzgHH2Gy3x4iPd2IL6DKOwCJuyu/M33rZlVxA3CQ5IPSHjcxGVXzjamYpY2J6YJn9YyblkA5sbghjnliAMixswMUsxvA8WNAZb1ZaXi55AIjhrPUxXMPewoog1WzLUChRH9vAVK0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774012899; c=relaxed/simple; bh=DOhmxg9F5bU2XleLRDRAytcCq0tQGfkZ6I8vMnEEcTA=; h=Date:Message-ID:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=WVtN07RUELbotVSOwvPAq0XnIFG8aVEfhl/CXvRSv3DyM5rv5TSNg47wQPuaufd1OuxyvKOCJU8KkRB27TjJ+b3TvDusbEwKeHd9dQ+d8Ny3VJFVNVzQ365gDOPIwLAUVaxZSpAUqXvNzQR31ZZToDLmycHlrPYfwgqgB0OlEjo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=vMMy8ePA; 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="vMMy8ePA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 50458C2BCAF; Fri, 20 Mar 2026 13:21:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774012898; bh=DOhmxg9F5bU2XleLRDRAytcCq0tQGfkZ6I8vMnEEcTA=; h=Date:From:To:Cc:Subject:References:From; b=vMMy8ePAxyDJFiaudHhN1f31Sv6RXN4pompWzwkYn2t+UkUDsdt0o6rjXPgwtuPor /ZxLZ8NsF4hzAvi/g8nWL7uqd+icuM9KNgbL9CqNRu5ajrWQnjo/CTpLmHCNF1CBF0 ENjlGRznFF+GDtZaCq8cUF60shyhJDOfAOTsybVV1dXXo8yQxBbUVcwvKZCGhnOrHs LnIr8wurvr8jGvH5fvxzRG2XrhbbuKq+G/Olam7ufxXY2R2AyC21D2LJE04p6gtpeX WgIPhXFAM48W48upWPfRPefdpEuGHu+bH4+qV/Dedezr2W3MsbMJOITIVCFqyOuWma InDkmOt2E8Jtg== Date: Fri, 20 Mar 2026 14:21:36 +0100 Message-ID: <20260320132102.162404736@kernel.org> User-Agent: quilt/0.68 From: Thomas Gleixner To: LKML Cc: x86@kernel.org, Dmitry Ilvokhin , Neil Horman , Radu Rendec Subject: [patch v2 02/14] genirq/proc: Avoid formatting zero counts in /proc/interrupts References: <20260320131108.344376329@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 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 --- 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);