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Message-ID: <aNrAKWRnPK1LskSg@shell.ilvokhin.com>
Date: Mon, 29 Sep 2025 17:21:45 +0000
From: Dmitry Ilvokhin <d@...okhin.com>
To: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
"H. Peter Anvin" <hpa@...or.com>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, kernel-team@...a.com
Subject: [PATCH] x86/irq: Optimize interrupts decimals printing
Function seq_printf supports rich format string for decimals printing,
but it doesn't required for printing /proc/interrupts per CPU counters,
seq_put_decimal_ull_width function can be used instead to print per CPU
counters, because very limited formatting is required for this case.
Performance counter stats (truncated) for 'sh -c cat /proc/interrupts
>/dev/null' (1000 runs) before and after applying the patch below.
Before:
3.42 msec task-clock # 0.802 CPUs utilized ( +- 0.05% )
1 context-switches # 291.991 /sec ( +- 0.74% )
0 cpu-migrations # 0.000 /sec
343 page-faults # 100.153 K/sec ( +- 0.01% )
8,932,242 instructions # 1.66 insn per cycle ( +- 0.34% )
5,374,427 cycles # 1.569 GHz ( +- 0.04% )
1,483,154 branches # 433.068 M/sec ( +- 0.22% )
28,768 branch-misses # 1.94% of all branches ( +- 0.31% )
0.00427182 +- 0.00000215 seconds time elapsed ( +- 0.05% )
After:
2.39 msec task-clock # 0.796 CPUs utilized ( +- 0.06% )
1 context-switches # 418.541 /sec ( +- 0.70% )
0 cpu-migrations # 0.000 /sec
343 page-faults # 143.560 K/sec ( +- 0.01% )
7,020,982 instructions # 1.30 insn per cycle ( +- 0.52% )
5,397,266 cycles # 2.259 GHz ( +- 0.06% )
1,569,648 branches # 656.962 M/sec ( +- 0.08% )
25,419 branch-misses # 1.62% of all branches ( +- 0.72% )
0.00299996 +- 0.00000206 seconds time elapsed ( +- 0.07% )
Signed-off-by: Dmitry Ilvokhin <d@...okhin.com>
---
arch/x86/kernel/irq.c | 96 +++++++++++++++++++++++--------------------
1 file changed, 52 insertions(+), 44 deletions(-)
diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index 10721a125226..3b5a5e2d16e1 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -61,6 +61,14 @@ void ack_bad_irq(unsigned int irq)
apic_eoi();
}
+static void put_spaced_decimal(struct seq_file *p, unsigned long long num)
+{
+ const char *delimiter = " ";
+ unsigned int width = 10;
+
+ seq_put_decimal_ull_width(p, delimiter, num, width);
+}
+
#define irq_stats(x) (&per_cpu(irq_stat, x))
/*
* /proc/interrupts printing for arch specific interrupts
@@ -69,102 +77,102 @@ int arch_show_interrupts(struct seq_file *p, int prec)
{
int j;
- seq_printf(p, "%*s: ", prec, "NMI");
+ seq_printf(p, "%*s:", prec, "NMI");
for_each_online_cpu(j)
- seq_printf(p, "%10u ", irq_stats(j)->__nmi_count);
+ put_spaced_decimal(p, irq_stats(j)->__nmi_count);
seq_puts(p, " Non-maskable interrupts\n");
#ifdef CONFIG_X86_LOCAL_APIC
- seq_printf(p, "%*s: ", prec, "LOC");
+ seq_printf(p, "%*s:", prec, "LOC");
for_each_online_cpu(j)
- seq_printf(p, "%10u ", irq_stats(j)->apic_timer_irqs);
+ put_spaced_decimal(p, irq_stats(j)->apic_timer_irqs);
seq_puts(p, " Local timer interrupts\n");
- seq_printf(p, "%*s: ", prec, "SPU");
+ seq_printf(p, "%*s:", prec, "SPU");
for_each_online_cpu(j)
- seq_printf(p, "%10u ", irq_stats(j)->irq_spurious_count);
+ put_spaced_decimal(p, irq_stats(j)->irq_spurious_count);
seq_puts(p, " Spurious interrupts\n");
- seq_printf(p, "%*s: ", prec, "PMI");
+ seq_printf(p, "%*s:", prec, "PMI");
for_each_online_cpu(j)
- seq_printf(p, "%10u ", irq_stats(j)->apic_perf_irqs);
+ put_spaced_decimal(p, irq_stats(j)->apic_perf_irqs);
seq_puts(p, " Performance monitoring interrupts\n");
- seq_printf(p, "%*s: ", prec, "IWI");
+ seq_printf(p, "%*s:", prec, "IWI");
for_each_online_cpu(j)
- seq_printf(p, "%10u ", irq_stats(j)->apic_irq_work_irqs);
+ put_spaced_decimal(p, irq_stats(j)->apic_irq_work_irqs);
seq_puts(p, " IRQ work interrupts\n");
- seq_printf(p, "%*s: ", prec, "RTR");
+ seq_printf(p, "%*s:", prec, "RTR");
for_each_online_cpu(j)
- seq_printf(p, "%10u ", irq_stats(j)->icr_read_retry_count);
+ put_spaced_decimal(p, irq_stats(j)->icr_read_retry_count);
seq_puts(p, " APIC ICR read retries\n");
if (x86_platform_ipi_callback) {
- seq_printf(p, "%*s: ", prec, "PLT");
+ seq_printf(p, "%*s:", prec, "PLT");
for_each_online_cpu(j)
- seq_printf(p, "%10u ", irq_stats(j)->x86_platform_ipis);
+ put_spaced_decimal(p, irq_stats(j)->x86_platform_ipis);
seq_puts(p, " Platform interrupts\n");
}
#endif
#ifdef CONFIG_SMP
- seq_printf(p, "%*s: ", prec, "RES");
+ seq_printf(p, "%*s:", prec, "RES");
for_each_online_cpu(j)
- seq_printf(p, "%10u ", irq_stats(j)->irq_resched_count);
+ put_spaced_decimal(p, irq_stats(j)->irq_resched_count);
seq_puts(p, " Rescheduling interrupts\n");
- seq_printf(p, "%*s: ", prec, "CAL");
+ seq_printf(p, "%*s:", prec, "CAL");
for_each_online_cpu(j)
- seq_printf(p, "%10u ", irq_stats(j)->irq_call_count);
+ put_spaced_decimal(p, irq_stats(j)->irq_call_count);
seq_puts(p, " Function call interrupts\n");
- seq_printf(p, "%*s: ", prec, "TLB");
+ seq_printf(p, "%*s:", prec, "TLB");
for_each_online_cpu(j)
- seq_printf(p, "%10u ", irq_stats(j)->irq_tlb_count);
+ put_spaced_decimal(p, irq_stats(j)->irq_tlb_count);
seq_puts(p, " TLB shootdowns\n");
#endif
#ifdef CONFIG_X86_THERMAL_VECTOR
- seq_printf(p, "%*s: ", prec, "TRM");
+ seq_printf(p, "%*s:", prec, "TRM");
for_each_online_cpu(j)
- seq_printf(p, "%10u ", irq_stats(j)->irq_thermal_count);
+ put_spaced_decimal(p, irq_stats(j)->irq_thermal_count);
seq_puts(p, " Thermal event interrupts\n");
#endif
#ifdef CONFIG_X86_MCE_THRESHOLD
- seq_printf(p, "%*s: ", prec, "THR");
+ seq_printf(p, "%*s:", prec, "THR");
for_each_online_cpu(j)
- seq_printf(p, "%10u ", irq_stats(j)->irq_threshold_count);
+ put_spaced_decimal(p, irq_stats(j)->irq_threshold_count);
seq_puts(p, " Threshold APIC interrupts\n");
#endif
#ifdef CONFIG_X86_MCE_AMD
- seq_printf(p, "%*s: ", prec, "DFR");
+ seq_printf(p, "%*s:", prec, "DFR");
for_each_online_cpu(j)
- seq_printf(p, "%10u ", irq_stats(j)->irq_deferred_error_count);
+ put_spaced_decimal(p, irq_stats(j)->irq_deferred_error_count);
seq_puts(p, " Deferred Error APIC interrupts\n");
#endif
#ifdef CONFIG_X86_MCE
- seq_printf(p, "%*s: ", prec, "MCE");
+ seq_printf(p, "%*s:", prec, "MCE");
for_each_online_cpu(j)
- seq_printf(p, "%10u ", per_cpu(mce_exception_count, j));
+ put_spaced_decimal(p, per_cpu(mce_exception_count, j));
seq_puts(p, " Machine check exceptions\n");
- seq_printf(p, "%*s: ", prec, "MCP");
+ seq_printf(p, "%*s:", prec, "MCP");
for_each_online_cpu(j)
- seq_printf(p, "%10u ", per_cpu(mce_poll_count, j));
+ put_spaced_decimal(p, per_cpu(mce_poll_count, j));
seq_puts(p, " Machine check polls\n");
#endif
#ifdef CONFIG_X86_HV_CALLBACK_VECTOR
if (test_bit(HYPERVISOR_CALLBACK_VECTOR, system_vectors)) {
- seq_printf(p, "%*s: ", prec, "HYP");
+ seq_printf(p, "%*s:", prec, "HYP");
for_each_online_cpu(j)
- seq_printf(p, "%10u ",
+ put_spaced_decimal(p,
irq_stats(j)->irq_hv_callback_count);
seq_puts(p, " Hypervisor callback interrupts\n");
}
#endif
#if IS_ENABLED(CONFIG_HYPERV)
if (test_bit(HYPERV_REENLIGHTENMENT_VECTOR, system_vectors)) {
- seq_printf(p, "%*s: ", prec, "HRE");
+ seq_printf(p, "%*s:", prec, "HRE");
for_each_online_cpu(j)
- seq_printf(p, "%10u ",
+ put_spaced_decimal(p,
irq_stats(j)->irq_hv_reenlightenment_count);
seq_puts(p, " Hyper-V reenlightenment interrupts\n");
}
if (test_bit(HYPERV_STIMER0_VECTOR, system_vectors)) {
- seq_printf(p, "%*s: ", prec, "HVS");
+ seq_printf(p, "%*s:", prec, "HVS");
for_each_online_cpu(j)
- seq_printf(p, "%10u ",
+ put_spaced_decimal(p,
irq_stats(j)->hyperv_stimer0_count);
seq_puts(p, " Hyper-V stimer0 interrupts\n");
}
@@ -174,27 +182,27 @@ int arch_show_interrupts(struct seq_file *p, int prec)
seq_printf(p, "%*s: %10u\n", prec, "MIS", atomic_read(&irq_mis_count));
#endif
#if IS_ENABLED(CONFIG_KVM)
- seq_printf(p, "%*s: ", prec, "PIN");
+ seq_printf(p, "%*s:", prec, "PIN");
for_each_online_cpu(j)
- seq_printf(p, "%10u ", irq_stats(j)->kvm_posted_intr_ipis);
+ put_spaced_decimal(p, irq_stats(j)->kvm_posted_intr_ipis);
seq_puts(p, " Posted-interrupt notification event\n");
- seq_printf(p, "%*s: ", prec, "NPI");
+ seq_printf(p, "%*s:", prec, "NPI");
for_each_online_cpu(j)
- seq_printf(p, "%10u ",
+ put_spaced_decimal(p,
irq_stats(j)->kvm_posted_intr_nested_ipis);
seq_puts(p, " Nested posted-interrupt event\n");
- seq_printf(p, "%*s: ", prec, "PIW");
+ seq_printf(p, "%*s:", prec, "PIW");
for_each_online_cpu(j)
- seq_printf(p, "%10u ",
+ put_spaced_decimal(p,
irq_stats(j)->kvm_posted_intr_wakeup_ipis);
seq_puts(p, " Posted-interrupt wakeup event\n");
#endif
#ifdef CONFIG_X86_POSTED_MSI
- seq_printf(p, "%*s: ", prec, "PMN");
+ seq_printf(p, "%*s:", prec, "PMN");
for_each_online_cpu(j)
- seq_printf(p, "%10u ",
+ put_spaced_decimal(p,
irq_stats(j)->posted_msi_notification_count);
seq_puts(p, " Posted MSI notification event\n");
#endif
--
2.47.3
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