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x86/irq: Suppress unlikely interrupt stats by default

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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 <tglx@kernel.org>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Radu Rendec <radu@rendec.net>
Link: https://patch.msgid.link/20260517194931.276486277@kernel.org
This commit is contained in:
Thomas Gleixner 2026-05-17 22:01:54 +02:00
parent 2b57c69917
commit 8713f2e596
4 changed files with 31 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/x86/include/asm/hardirq.h
View File

@ -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)

2
arch/x86/kernel/apic/apic.c
View File

@ -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

2
arch/x86/kernel/apic/ipi.c
View File

@ -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;

38
arch/x86/kernel/irq.c
View File

@ -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);