From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 1CF871C860A for ; Fri, 29 May 2026 07:46:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780040800; cv=none; b=KcUn/pPuBCkD5HbUdVkQs1pbdxii1sVg+GmIZZumsatvumMdopEAhUwNkLXY1uLxWlF0i3z5vvhApORmwbDAtkrm8M3rkUJ66er7KIBX5FT2X7QNAGr3x0lZjeaQMqZiGKU8+rKR8kYSlnW6GVg02zJ1COFxjDE4Jf2A2MzhZvE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780040800; c=relaxed/simple; bh=KTzdLRHWJ74g43nh70P6oAIxSrcylpBE7kaX79qCVkI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=jkB9Vf26/OZeztvP2VX94O3M+jyyXxZayjo0yLjG2eVnHG6gLQSJC3prydb52u/HO7BgIPrxzem5yG1F/hVORw7eL5yDwxLEJofYPOIHYgFNeS0R9WoiGPPDXihJtRXFRK66F+RebPokJ7MoAH5oYKmEXdICy1tWWXufpKyIxuM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Zvs5TTU6; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Zvs5TTU6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1AC231F00893; Fri, 29 May 2026 07:46:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780040798; bh=/9CHHWmBxbO285j3s+oErzUVtg40ZUJ8QQ4Gwq27hes=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=Zvs5TTU67/6xKtZWmPKdtyYCfQ6apR7ef+zeu0Nb/UY6Wnel89+2ATf15FT79A03U E7aRfF4CCWsGvrXbimoDOSbnPIn2GMRzmwq6QYRf6w45P3+wMNCxxOPFfWUjukgsrr 1oIOHJLT+1j4Mz7xUw8PEd3YhKbQdxCB5AcaLyOgfS+/SnnGk52GX0TGPH84HmTOJf jUejFiFWKSPvEXEqQgMGxGDxvUFRmUqg3OcJOgqevWkhRXyYzsn793Q8iIuCCvUb7Q lAbkJJ9C2RTwD0gRYTtjX//zzTifHYVksT+LA75Og65b4j52mAgOSXCg6u70M4en3C K+WThV7ZXjOtQ== Message-ID: <1f0b54f5-1df0-4649-89bc-9ab3a6d9a100@kernel.org> Date: Fri, 29 May 2026 09:46:35 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/3] powerpc/irq: Make irqstats array based To: Shrikanth Hegde , maddy@linux.ibm.com, linuxppc-dev@lists.ozlabs.org, tglx@kernel.org Cc: linux-kernel@vger.kernel.org References: <20260523174016.999456-1-sshegde@linux.ibm.com> <20260523174016.999456-3-sshegde@linux.ibm.com> Content-Language: fr-FR From: "Christophe Leroy (CS GROUP)" In-Reply-To: <20260523174016.999456-3-sshegde@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Le 23/05/2026 à 19:40, Shrikanth Hegde a écrit : > Current irq_cpustat_t has separate member for handling each arch > specific interrupt type. The same can be achieved with array instead > indexed by corresponding irq counter type. > > This helps to, > > - Make it easy to integrate into genirq improvements by calling > genirq provided irq_proc_emit_counts. That speeds up quite a bit > by printing all 0's once as much as possible. > > - Adding a new vector or software counter only requires to update the table > and everything just works > > - Remove ifdef usage a bit. > > - Instead of going through each member, it simply becomes an array > traversal. > > Time taken to read /proc/interrupts 1000 times. > Base and v6 details can be found in cover-letter. > Base : 103us > v6 : 63us > v6+this_patch : 57us > > A Decent 10% reduction can be seen in a system 240 CPUs. As the system > size increases the gain would be more as emitting 0 would reduce more > and more. > > Signed-off-by: Shrikanth Hegde Reviewed-by: Christophe Leroy (CS GROUP) > --- > arch/powerpc/include/asm/hardirq.h | 27 +++++--- > arch/powerpc/kernel/dbell.c | 2 +- > arch/powerpc/kernel/irq.c | 107 ++++++++++------------------- > arch/powerpc/kernel/time.c | 6 +- > arch/powerpc/kernel/traps.c | 11 ++- > arch/powerpc/kernel/watchdog.c | 2 +- > 6 files changed, 64 insertions(+), 91 deletions(-) > > diff --git a/arch/powerpc/include/asm/hardirq.h b/arch/powerpc/include/asm/hardirq.h > index bf3926a0c69c..38098e35b241 100644 > --- a/arch/powerpc/include/asm/hardirq.h > +++ b/arch/powerpc/include/asm/hardirq.h > @@ -5,26 +5,33 @@ > #include > #include > > -typedef struct { > - unsigned int timer_irqs_event; > - unsigned int broadcast_irqs_event; > - unsigned int timer_irqs_others; > - unsigned int pmu_irqs; > - unsigned int mce_exceptions; > - unsigned int spurious_irqs; > - unsigned int sreset_irqs; > +enum irq_stat_counts { > + IRQ_COUNT_LOC_TIMER, > + IRQ_COUNT_BCT_TIMER, > + IRQ_COUNT_OTHER_TIMER, > + IRQ_COUNT_SPURIOUS, > + IRQ_COUNT_PMI, > + IRQ_COUNT_MCE, > + IRQ_COUNT_NMI_SRESET, > #ifdef CONFIG_PPC_WATCHDOG > - unsigned int soft_nmi_irqs; > + IRQ_COUNT_WATCHDOG, > #endif > #ifdef CONFIG_PPC_DOORBELL > - unsigned int doorbell_irqs; > + IRQ_COUNT_DOORBELL, > #endif > + IRQ_COUNT_MAX, > +}; > + > +typedef struct { > + unsigned int counts[IRQ_COUNT_MAX]; > } ____cacheline_aligned irq_cpustat_t; > > DECLARE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat); > DECLARE_PER_CPU(unsigned int, __softirq_pending); > #define local_softirq_pending_ref __softirq_pending > > +#define inc_irq_stat(index) __this_cpu_inc(irq_stat.counts[IRQ_COUNT_##index]) > + > #define __ARCH_IRQ_STAT > #define __ARCH_IRQ_EXIT_IRQS_DISABLED > > diff --git a/arch/powerpc/kernel/dbell.c b/arch/powerpc/kernel/dbell.c > index 5712dd846263..f5e298a4c4c0 100644 > --- a/arch/powerpc/kernel/dbell.c > +++ b/arch/powerpc/kernel/dbell.c > @@ -31,7 +31,7 @@ DEFINE_INTERRUPT_HANDLER_ASYNC(doorbell_exception) > do_hard_irq_enable(); > > kvmppc_clear_host_ipi(smp_processor_id()); > - __this_cpu_inc(irq_stat.doorbell_irqs); > + inc_irq_stat(DOORBELL); > > smp_ipi_demux_relaxed(); /* already performed the barrier */ > > diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c > index f33df5e5c23f..e67a18f62142 100644 > --- a/arch/powerpc/kernel/irq.c > +++ b/arch/powerpc/kernel/irq.c > @@ -84,79 +84,57 @@ u32 tau_interrupts(unsigned long cpu); > #endif > #endif /* CONFIG_PPC32 */ > > +struct irq_stat_info { > + const char *symbol; > + const char *text; > +}; > + > +#define ISE(idx, sym, txt)[IRQ_COUNT_##idx] = { .symbol = sym, .text = txt} > + > +static struct irq_stat_info irq_stat_info[IRQ_COUNT_MAX] __ro_after_init = { > + ISE(LOC_TIMER, "LOC", " Local timer interrupts for timer event device\n"), > + ISE(BCT_TIMER, "BCT", " Broadcast timer interrupts for timer event device\n"), > + ISE(OTHER_TIMER, "LOC", " Local timer interrupts for others\n"), > + ISE(SPURIOUS, "SPU", " Spurious interrupts\n"), > + ISE(PMI, "PMI", " Performance monitoring interrupts\n"), > + ISE(MCE, "MCE", " Machine check exceptions\n"), > + ISE(NMI_SRESET, "NMI", " System Reset interrupts\n"), > +#ifdef CONFIG_PPC_WATCHDOG > + ISE(WATCHDOG, "WDG", " Watchdog soft-NMI interrupts\n"), > +#endif > +#ifdef CONFIG_PPC_DOORBELL > + ISE(DOORBELL, "DBL", " Doorbell interrupts\n"), > +#endif > +}; > + > int arch_show_interrupts(struct seq_file *p, int prec) > { > - int j; > + const struct irq_stat_info *info = irq_stat_info; > + > + for (unsigned int i = 0; i < ARRAY_SIZE(irq_stat_info); i++, info++) { > + seq_printf(p, "%*s:", prec, info->symbol); > + irq_proc_emit_counts(p, &irq_stat.counts[i]); > + seq_puts(p, info->text); > + } > > #if defined(CONFIG_PPC32) && defined(CONFIG_TAU_INT) > if (tau_initialized) { > + int j; > seq_printf(p, "%*s:", prec, "TAU"); > for_each_online_cpu(j) > seq_put_decimal_ull_width(p, " ", tau_interrupts(j), 10); > seq_puts(p, " PowerPC Thermal Assist (cpu temp)\n"); > } > #endif /* CONFIG_PPC32 && CONFIG_TAU_INT */ > - > - seq_printf(p, "%*s:", prec, "LOC"); > - for_each_online_cpu(j) > - seq_put_decimal_ull_width(p, " ", per_cpu(irq_stat, j).timer_irqs_event, 10); > - seq_printf(p, " Local timer interrupts for timer event device\n"); > - > - seq_printf(p, "%*s:", prec, "BCT"); > - for_each_online_cpu(j) > - seq_put_decimal_ull_width(p, " ", per_cpu(irq_stat, j).broadcast_irqs_event, 10); > - seq_printf(p, " Broadcast timer interrupts for timer event device\n"); > - > - seq_printf(p, "%*s:", prec, "LOC"); > - for_each_online_cpu(j) > - seq_put_decimal_ull_width(p, " ", per_cpu(irq_stat, j).timer_irqs_others, 10); > - seq_printf(p, " Local timer interrupts for others\n"); > - > - seq_printf(p, "%*s:", prec, "SPU"); > - for_each_online_cpu(j) > - seq_put_decimal_ull_width(p, " ", per_cpu(irq_stat, j).spurious_irqs, 10); > - seq_printf(p, " Spurious interrupts\n"); > - > - seq_printf(p, "%*s:", prec, "PMI"); > - for_each_online_cpu(j) > - seq_put_decimal_ull_width(p, " ", per_cpu(irq_stat, j).pmu_irqs, 10); > - seq_printf(p, " Performance monitoring interrupts\n"); > - > - seq_printf(p, "%*s:", prec, "MCE"); > - for_each_online_cpu(j) > - seq_put_decimal_ull_width(p, " ", per_cpu(irq_stat, j).mce_exceptions, 10); > - seq_printf(p, " Machine check exceptions\n"); > - > #ifdef CONFIG_PPC_BOOK3S_64 > if (cpu_has_feature(CPU_FTR_HVMODE)) { > + int j; > seq_printf(p, "%*s:", prec, "HMI"); > for_each_online_cpu(j) > seq_put_decimal_ull_width(p, " ", paca_ptrs[j]->hmi_irqs, 10); > seq_printf(p, " Hypervisor Maintenance Interrupts\n"); > } > #endif > - > - seq_printf(p, "%*s:", prec, "NMI"); > - for_each_online_cpu(j) > - seq_put_decimal_ull_width(p, " ", per_cpu(irq_stat, j).sreset_irqs, 10); > - seq_printf(p, " System Reset interrupts\n"); > - > -#ifdef CONFIG_PPC_WATCHDOG > - seq_printf(p, "%*s:", prec, "WDG"); > - for_each_online_cpu(j) > - seq_put_decimal_ull_width(p, " ", per_cpu(irq_stat, j).soft_nmi_irqs, 10); > - seq_printf(p, " Watchdog soft-NMI interrupts\n"); > -#endif > - > -#ifdef CONFIG_PPC_DOORBELL > - if (cpu_has_feature(CPU_FTR_DBELL)) { > - seq_printf(p, "%*s:", prec, "DBL"); > - for_each_online_cpu(j) > - seq_put_decimal_ull_width(p, " ", per_cpu(irq_stat, j).doorbell_irqs, 10); > - seq_printf(p, " Doorbell interrupts\n"); > - } > -#endif > - > return 0; > } > > @@ -165,24 +143,15 @@ int arch_show_interrupts(struct seq_file *p, int prec) > */ > u64 arch_irq_stat_cpu(unsigned int cpu) > { > - u64 sum = per_cpu(irq_stat, cpu).timer_irqs_event; > + irq_cpustat_t *p = per_cpu_ptr(&irq_stat, cpu); > + u64 sum = 0; > + > + for (unsigned int i = 0; i < ARRAY_SIZE(irq_stat_info); i++) > + sum += p->counts[i]; > > - sum += per_cpu(irq_stat, cpu).broadcast_irqs_event; > - sum += per_cpu(irq_stat, cpu).pmu_irqs; > - sum += per_cpu(irq_stat, cpu).mce_exceptions; > - sum += per_cpu(irq_stat, cpu).spurious_irqs; > - sum += per_cpu(irq_stat, cpu).timer_irqs_others; > #ifdef CONFIG_PPC_BOOK3S_64 > sum += paca_ptrs[cpu]->hmi_irqs; > #endif > - sum += per_cpu(irq_stat, cpu).sreset_irqs; > -#ifdef CONFIG_PPC_WATCHDOG > - sum += per_cpu(irq_stat, cpu).soft_nmi_irqs; > -#endif > -#ifdef CONFIG_PPC_DOORBELL > - sum += per_cpu(irq_stat, cpu).doorbell_irqs; > -#endif > - > return sum; > } > > @@ -248,7 +217,7 @@ static void __do_irq(struct pt_regs *regs, unsigned long oldsp) > > /* And finally process it */ > if (unlikely(!irq)) > - __this_cpu_inc(irq_stat.spurious_irqs); > + inc_irq_stat(SPURIOUS); > else > generic_handle_irq(irq); > > diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c > index 4bbeb8644d3d..44da7be36199 100644 > --- a/arch/powerpc/kernel/time.c > +++ b/arch/powerpc/kernel/time.c > @@ -572,13 +572,13 @@ DEFINE_INTERRUPT_HANDLER_ASYNC(timer_interrupt) > now = get_tb(); > if (now >= *next_tb) { > evt->event_handler(evt); > - __this_cpu_inc(irq_stat.timer_irqs_event); > + inc_irq_stat(LOC_TIMER); > } else { > now = *next_tb - now; > if (now > decrementer_max) > now = decrementer_max; > set_dec_or_work(now); > - __this_cpu_inc(irq_stat.timer_irqs_others); > + inc_irq_stat(OTHER_TIMER); > } > > trace_timer_interrupt_exit(regs); > @@ -591,7 +591,7 @@ EXPORT_SYMBOL(timer_interrupt); > void timer_broadcast_interrupt(void) > { > tick_receive_broadcast(); > - __this_cpu_inc(irq_stat.broadcast_irqs_event); > + inc_irq_stat(BCT_TIMER); > } > #endif > > diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c > index cb8e9357383e..a8f15154bd9a 100644 > --- a/arch/powerpc/kernel/traps.c > +++ b/arch/powerpc/kernel/traps.c > @@ -459,8 +459,7 @@ DEFINE_INTERRUPT_HANDLER_NMI(system_reset_exception) > } > > hv_nmi_check_nonrecoverable(regs); > - > - __this_cpu_inc(irq_stat.sreset_irqs); > + inc_irq_stat(NMI_SRESET); > > /* See if any machine dependent calls */ > if (ppc_md.system_reset_exception) { > @@ -817,7 +816,7 @@ static void __machine_check_exception(struct pt_regs *regs) > { > int recover = 0; > > - __this_cpu_inc(irq_stat.mce_exceptions); > + inc_irq_stat(MCE); > > add_taint(TAINT_MACHINE_CHECK, LOCKDEP_NOW_UNRELIABLE); > > @@ -1932,8 +1931,7 @@ DEFINE_INTERRUPT_HANDLER(vsx_unavailable_tm) > DECLARE_INTERRUPT_HANDLER_NMI(performance_monitor_exception_nmi); > DEFINE_INTERRUPT_HANDLER_NMI(performance_monitor_exception_nmi) > { > - __this_cpu_inc(irq_stat.pmu_irqs); > - > + inc_irq_stat(PMI); > perf_irq(regs); > > return 0; > @@ -1943,8 +1941,7 @@ DEFINE_INTERRUPT_HANDLER_NMI(performance_monitor_exception_nmi) > DECLARE_INTERRUPT_HANDLER_ASYNC(performance_monitor_exception_async); > DEFINE_INTERRUPT_HANDLER_ASYNC(performance_monitor_exception_async) > { > - __this_cpu_inc(irq_stat.pmu_irqs); > - > + inc_irq_stat(PMI); > perf_irq(regs); > } > > diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c > index 764001deb060..f516eeccc9f6 100644 > --- a/arch/powerpc/kernel/watchdog.c > +++ b/arch/powerpc/kernel/watchdog.c > @@ -381,7 +381,7 @@ DEFINE_INTERRUPT_HANDLER_NMI(soft_nmi_interrupt) > if (!cpumask_test_cpu(cpu, &wd_cpus_enabled)) > return 0; > > - __this_cpu_inc(irq_stat.soft_nmi_irqs); > + inc_irq_stat(WATCHDOG); > > tb = get_tb(); > if (tb - per_cpu(wd_timer_tb, cpu) >= wd_panic_timeout_tb) {