[PATCH 2/3] powerpc/irq: Make irqstats array based
From: Shrikanth Hegde <hidden>
Date: 2026-05-23 17:41:16
Also in:
lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
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 <redacted> --- 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 <linux/threads.h> #include <linux/irq.h> -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) {
--
2.47.3