Re: [PATCH v1] x86/dovetail: pipeline the thermal APIC sysvec

On Tue, 2026-08-11 at 20:05 +0800, liuyang wrote:
> sysvec_thermal was a non-pipelined DEFINE_IDTENTRY_SYSVEC (with a real
> __apic_eoi()). Under thermal load we still hit stalls while that
> handler ran against in-band timer paths (therm_throt_process ->
> add_timer_on).
> 
> Handle THERMAL_APIC_VECTOR as a pipelined sysvec and dispatch it from
> do_sysvec_inband(), so thermal runs on the in-band stage like other
> pipelined system vectors.

[ To +Philippe as the "Dovetail" prefix is missing in the subject line ]

Reviewed-by: Florian Bezdeka <[email protected]>

> 
> Signed-off-by: liuyang <[email protected]>
> ---
>  arch/x86/include/asm/idtentry.h | 2 +-
>  arch/x86/kernel/irq.c           | 5 +++--
>  arch/x86/kernel/irq_pipeline.c  | 5 +++++
>  3 files changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
> index bb1df662d..b8d4995f9 100644
> --- a/arch/x86/include/asm/idtentry.h
> +++ b/arch/x86/include/asm/idtentry.h
> @@ -816,7 +816,7 @@ DECLARE_IDTENTRY_SYSVEC(DEFERRED_ERROR_VECTOR,		sysvec_deferred_error);
>  # endif
> 
>  # ifdef CONFIG_X86_THERMAL_VECTOR
> -DECLARE_IDTENTRY_SYSVEC(THERMAL_APIC_VECTOR,		sysvec_thermal);
> +DECLARE_IDTENTRY_SYSVEC_PIPELINED(THERMAL_APIC_VECTOR,		sysvec_thermal);
>  # else
>  # define fred_sysvec_thermal				NULL
>  # endif
> diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
> index f745f1752..976828a63 100644
> --- a/arch/x86/kernel/irq.c
> +++ b/arch/x86/kernel/irq.c
> @@ -582,12 +582,13 @@ static void smp_thermal_vector(void)
>  		       smp_processor_id());
>  }
> 
> -DEFINE_IDTENTRY_SYSVEC(sysvec_thermal)
> +DEFINE_IDTENTRY_SYSVEC_PIPELINED(THERMAL_APIC_VECTOR,
> +				sysvec_thermal)
>  {
>  	trace_thermal_apic_entry(THERMAL_APIC_VECTOR);
>  	inc_irq_stat(irq_thermal_count);
>  	smp_thermal_vector();
>  	trace_thermal_apic_exit(THERMAL_APIC_VECTOR);
> -	__apic_eoi();
> +	apic_eoi();
>  }
>  #endif
> diff --git a/arch/x86/kernel/irq_pipeline.c b/arch/x86/kernel/irq_pipeline.c
> index 00cb779a2..cb267c2e0 100644
> --- a/arch/x86/kernel/irq_pipeline.c
> +++ b/arch/x86/kernel/irq_pipeline.c
> @@ -176,6 +176,11 @@ static void do_sysvec_inband(struct irq_desc *desc, struct pt_regs *regs)
>  	case LOCAL_TIMER_VECTOR:
>  		run_sysvec_on_irqstack_cond(__sysvec_apic_timer_interrupt, regs);
>  		break;
> +#ifdef CONFIG_X86_THERMAL_VECTOR
> +	case THERMAL_APIC_VECTOR:
> +		run_sysvec_on_irqstack_cond(__sysvec_thermal, regs);
> +		break;
> +#endif
>  	default:
>  		printk_once(KERN_ERR "irq_pipeline: unexpected event"
>  			" on vector #%.2x (irq=%u)", vector, irq);
> --
> 2.34.1