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 623D13CE49B for ; Wed, 4 Mar 2026 18:55:39 +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=1772650539; cv=none; b=kryTHx1gWPUAkC28F4eYQBBakeeZzPG4qdxHiN3pDQApQK3Zp8SJWRRDrDij2G1OZcmVOOWIbbXR92Eey4bxpoQCL5ntuM+LzDgr/ei/hQXPcuG/d9MS0c2hkyRPqmIHl6pHfrZyfhi/alQNFybm7BVWHm3x+WZtmCacycPCHwY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772650539; c=relaxed/simple; bh=8kSxdhX4H/+8X510szjjiKOKnfifKZh1pmVxuuSMnNE=; h=Date:Message-ID:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=XE/hpueFa+qKSYNXw8NzwJgVLLe2tuly2laxkcbo34kBHLJNg1PynxjZPT7cjgwcmzW8noMXynDHWh+UUNbxS09CseDAl1td4s6GrO5Zbj1U2+uM1cpmLudHdC6hZDSGd+7zU1aBPI+kxhkUu1oHm4kwlhGhi9S2Cgeld6Sl5XY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rS6eFOux; 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="rS6eFOux" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D29F2C19425; Wed, 4 Mar 2026 18:55:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772650539; bh=8kSxdhX4H/+8X510szjjiKOKnfifKZh1pmVxuuSMnNE=; h=Date:From:To:Cc:Subject:References:From; b=rS6eFOuxH9Jpsyc4ntCTRjY3dghaLIsycNSTpwJCYzumd0/uiEeMDS5dVdGqKqSjw 0eBVSfJuYe2owGI5pgeL7XPZoz2ppu3vmWh3lmR9oj+CxPUP6QBFRXeYI3mCpZXH2K TFMD0ym3UwaPEOew5oH1qHo4Qd5rfLEAfx48IVqBdNgpskFCCklZP4rtnYGRuEDu3m JGqkV6BV4m+f62GSDIdbTmj5D17sm3U17UGUQD6OyMJv/BPJYHSYr4xDf/0USlLTwP KeUOro2XJ5B1uOJGGPj+s0MGonkb3ogZNfmr3f1Zw236w/FdZfTQ1sCx916cChPO1M bG/nHf9gCRLSQ== Date: Wed, 04 Mar 2026 19:55:36 +0100 Message-ID: <20260303154548.082654896@kernel.org> User-Agent: quilt/0.68 From: Thomas Gleixner To: LKML Cc: x86@kernel.org, Dmitry Ilvokhin , Neil Horman Subject: [patch 02/14] genirq/proc: Avoid formatting zero counts in /proc/interrupts References: <20260303150539.513068586@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 --- 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 11 +#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);