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 7FE242D63E8 for ; Sun, 17 May 2026 20:01:42 +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=1779048102; cv=none; b=fRBTtyuouP7UuTfsutrwmnUVsezhdx8Ixp8d4Jz1qZRToDE16oGPQ8Ps9Dw3i5Z9ME7nKhSrEeIpik3IStaz7GxrRPm2DQ2DS2AGZP9+SmccSqgVnd126E7uKyfuYqCK7dLJWODyiSSplh7ifZq17TgJa38WPbdUnDD1WtSY/Go= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779048102; c=relaxed/simple; bh=byaY/Nig/nXkacnJTTiCfke3c3h49cDdpaO7T37JjRA=; h=Date:Message-ID:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=jOsy/8rwdvQjuKAEfP/AM5g2/2ViXYJHUVJddSv4n0LwJgay6RYw0H9f4dopo4H9pRKn/AJSjWBhnqdjWs4yME2WzIlHfSzE296TTJ714UaLgobaIvTDGiz2fxg8bCi50vfhm7mqfViiDezGYHQdN6O5WBMxPzUTiSB0eslNHBM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=B3ba5A1X; 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="B3ba5A1X" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9C86BC2BCF6; Sun, 17 May 2026 20:01:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1779048102; bh=byaY/Nig/nXkacnJTTiCfke3c3h49cDdpaO7T37JjRA=; h=Date:From:To:Cc:Subject:References:From; b=B3ba5A1X0CYyxFIZhTynE+kaFs2kOfgQGz1POcRDbohgq1BR9VyApapk408DnoTLu Bbq4IY+97XYe1j32tk3TJxkYWsUhl2/Nm5opGv9wFtGutUw2E9m4Af90kQ2gsvKiUb vusnTm+l4Awk+f5hlepbCairaRBKm88JkkMRq18b6t7WV9C7HtiuJbmxd8NNjHPQLK c+TROgXeQR9BfmLJlXVAgkSYtxMLgdO7XDyPG/YrQR6MpAfBHX7aiHLnjbfLeOToeC 29dWKbKGrRedUTYOfaKwq4duGTVAXE0CJhJXNXMDwQz3e4V1gVJo28WMGpxd+rTtEy mQ4kVABq+ZJxg== Date: Sun, 17 May 2026 22:01:38 +0200 Message-ID: <20260517194931.034728540@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 V6 02/16] genirq/proc: Avoid formatting zero counts in /proc/interrupts References: <20260517194421.705253664@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 Tested-by: Michael Kelley Reviewed-by: Dmitry Ilvokhin Reviewed-by: Radu Rendec --- V2: Use sizeof() for ZSTR1_LEN - Dmitry --- include/linux/interrupt.h | 1 + kernel/irq/proc.c | 43 ++++++++++++++++++++++++++++++++++++++----- 2 files changed, 39 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 +450,43 @@ int __weak arch_show_interrupts(struct s # define ACTUAL_NR_IRQS irq_get_nr_irqs() #endif +/* Same as seq_put_decimal_ull_width(p, " ", cnt, 10) */ +#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 +522,7 @@ 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);