From: Thomas Gleixner Date: Sun, 17 May 2026 20:01:54 +0000 (+0200) Subject: x86/irq: Suppress unlikely interrupt stats by default X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=8713f2e596a134ed5c41e96bb9714251a5e6d56a;p=thirdparty%2Flinux.git x86/irq: Suppress unlikely interrupt stats by default Unlikely interrupt counters like the spurious vector and the synthetic APIC ICR read retry show up in /proc/interrupts with all counts 0 most of the time. As these are events which should never happen, suppress them by default and enable them for output when they actually happen. This requires a seperate bitmap as the description array is marked __ro_after_init. With that bitmap in place it becomes RO data. Signed-off-by: Thomas Gleixner Tested-by: Michael Kelley Reviewed-by: Radu Rendec Link: https://patch.msgid.link/20260517194931.276486277@kernel.org --- diff --git a/arch/x86/include/asm/hardirq.h b/arch/x86/include/asm/hardirq.h index 423fa4d068a7d..6723b512c6944 100644 --- a/arch/x86/include/asm/hardirq.h +++ b/arch/x86/include/asm/hardirq.h @@ -68,6 +68,7 @@ DECLARE_PER_CPU_ALIGNED(struct pi_desc, posted_msi_pi_desc); #define __ARCH_IRQ_STAT #define inc_irq_stat(index) this_cpu_inc(irq_stat.counts[IRQ_COUNT_##index]) +void irq_stat_inc_and_enable(enum irq_stat_counts which); #ifdef CONFIG_X86_LOCAL_APIC #define inc_perf_irq_stat() inc_irq_stat(APIC_PERF) diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index 6599e8004d94a..e27c263d6c13b 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -2114,7 +2114,7 @@ static noinline void handle_spurious_interrupt(u8 vector) trace_spurious_apic_entry(vector); - inc_irq_stat(SPURIOUS); + irq_stat_inc_and_enable(IRQ_COUNT_SPURIOUS); /* * If this is a spurious interrupt then do not acknowledge diff --git a/arch/x86/kernel/apic/ipi.c b/arch/x86/kernel/apic/ipi.c index 3635c4d7b7f5c..c627bee3b14f7 100644 --- a/arch/x86/kernel/apic/ipi.c +++ b/arch/x86/kernel/apic/ipi.c @@ -120,7 +120,7 @@ u32 apic_mem_wait_icr_idle_timeout(void) for (cnt = 0; cnt < 1000; cnt++) { if (!(apic_read(APIC_ICR) & APIC_ICR_BUSY)) return 0; - inc_irq_stat(ICR_READ_RETRY); + irq_stat_inc_and_enable(IRQ_COUNT_ICR_READ_RETRY); udelay(100); } return APIC_ICR_BUSY; diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c index decd08d3d3151..2d8ca41166108 100644 --- a/arch/x86/kernel/irq.c +++ b/arch/x86/kernel/irq.c @@ -68,19 +68,24 @@ struct irq_stat_info { const char *text; }; +#define DEFAULT_SUPPRESSED_VECTOR UINT_MAX + #define ISS(idx, sym, txt) [IRQ_COUNT_##idx] = { .symbol = sym, .text = txt } #define ITS(idx, sym, txt) [IRQ_COUNT_##idx] = \ { .skip_vector = idx## _VECTOR, .symbol = sym, .text = txt } -static struct irq_stat_info irq_stat_info[IRQ_COUNT_MAX] __ro_after_init = { +#define IDS(idx, sym, txt) [IRQ_COUNT_##idx] = \ + { .skip_vector = DEFAULT_SUPPRESSED_VECTOR, .symbol = sym, .text = txt } + +static const struct irq_stat_info irq_stat_info[IRQ_COUNT_MAX] = { ISS(NMI, "NMI", " Non-maskable interrupts\n"), #ifdef CONFIG_X86_LOCAL_APIC ISS(APIC_TIMER, "LOC", " Local timer interrupts\n"), - ISS(SPURIOUS, "SPU", " Spurious interrupts\n"), + IDS(SPURIOUS, "SPU", " Spurious interrupts\n"), ISS(APIC_PERF, "PMI", " Performance monitoring interrupts\n"), ISS(IRQ_WORK, "IWI", " IRQ work interrupts\n"), - ISS(ICR_READ_RETRY, "RTR", " APIC ICR read retries\n"), + IDS(ICR_READ_RETRY, "RTR", " APIC ICR read retries\n"), ISS(X86_PLATFORM_IPI, "PLT", " Platform interrupts\n"), #endif #ifdef CONFIG_SMP @@ -121,34 +126,47 @@ static struct irq_stat_info irq_stat_info[IRQ_COUNT_MAX] __ro_after_init = { #endif }; +static DECLARE_BITMAP(irq_stat_count_show, IRQ_COUNT_MAX) __read_mostly; + static int __init irq_init_stats(void) { - struct irq_stat_info *info = irq_stat_info; + const struct irq_stat_info *info = irq_stat_info; for (unsigned int i = 0; i < ARRAY_SIZE(irq_stat_info); i++, info++) { - if (info->skip_vector && test_bit(info->skip_vector, system_vectors)) - info->skip_vector = 0; + if (!info->skip_vector || (info->skip_vector != DEFAULT_SUPPRESSED_VECTOR && + test_bit(info->skip_vector, system_vectors))) + set_bit(i, irq_stat_count_show); } #ifdef CONFIG_X86_LOCAL_APIC if (!x86_platform_ipi_callback) - irq_stat_info[IRQ_COUNT_X86_PLATFORM_IPI].skip_vector = 1; + clear_bit(IRQ_COUNT_X86_PLATFORM_IPI, irq_stat_count_show); #endif #ifdef CONFIG_X86_POSTED_MSI if (!posted_msi_enabled()) - irq_stat_info[IRQ_COUNT_POSTED_MSI_NOTIFICATION].skip_vector = 1; + clear_bit(IRQ_COUNT_POSTED_MSI_NOTIFICATION, irq_stat_count_show); #endif #ifdef CONFIG_X86_MCE_AMD if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD && boot_cpu_data.x86_vendor != X86_VENDOR_HYGON) - irq_stat_info[IRQ_COUNT_DEFERRED_ERROR].skip_vector = 1; + clear_bit(IRQ_COUNT_DEFERRED_ERROR, irq_stat_count_show); #endif return 0; } late_initcall(irq_init_stats); +/* + * Used for default disabled counters to increment the stats and to enable the + * entry for /proc/interrupts output. + */ +void irq_stat_inc_and_enable(enum irq_stat_counts which) +{ + this_cpu_inc(irq_stat.counts[which]); + set_bit(which, irq_stat_count_show); +} + #ifdef CONFIG_PROC_FS /* * /proc/interrupts printing for arch specific interrupts @@ -158,7 +176,7 @@ int arch_show_interrupts(struct seq_file *p, int prec) const struct irq_stat_info *info = irq_stat_info; for (unsigned int i = 0; i < ARRAY_SIZE(irq_stat_info); i++, info++) { - if (info->skip_vector) + if (!test_bit(i, irq_stat_count_show)) continue; seq_printf(p, "%*s:", prec, info->symbol);