RE: [patch v2 04/14] x86/irq: Make irqstats array based

[Michael Kelley]

From: Thomas Gleixner <tglx@xxxxxxxxxx> Sent: Friday, March 20, 2026 6:22 AM
> 
> Having the x86 specific interrupt statistics as a data structure with
> individual members instead of an array is just stupid as it requires
> endless copy and paste in arch_show_interrupts() and arch_irq_stat_cpu(),
> where the latter does not even take the latest interrupt additions into
> account. The resulting #ifdef orgy is just disgusting.
> 
> Convert it to an array of counters, which does not make a difference in the
> actual interrupt hotpath increment as the array index is constant and
> therefore not any different than the member based access.
> 
> But in arch_show_interrupts() and arch_irq_stat_cpu() this just turns into
> a loop, which reduces the text size by ~2k (~12%):
> 
>    text	   data	    bss	    dec	    hex	filename
>   19643	  15250	    904	  35797	   8bd5	../build/arch/x86/kernel/irq.o
>   17355	  15250	    904	  33509	   82e5	../build/arch/x86/kernel/irq.o
> 
> Adding a new vector or software counter only requires to update the table
> and everything just works. Using the core provided emit function which
> speeds up 0 outputs makes it significantly faster.
> 
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxx>
> ---
> V2: Simplified and extended vector skip mechanism
>     Fixup the typoes - Micheal, Dmitry
>     Added the lost precision back for ERR/MIS - Dmitry

[snip]

>  #if IS_ENABLED(CONFIG_HYPERV)
> -	if (test_bit(HYPERV_REENLIGHTENMENT_VECTOR, system_vectors)) {
> -		seq_printf(p, "%*s:", prec, "HRE");
> -		for_each_online_cpu(j)
> -			put_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");
> -		for_each_online_cpu(j)
> -			put_decimal(p, irq_stats(j)->hyperv_stimer0_count);
> -		seq_puts(p, "  Hyper-V stimer0 interrupts\n");
> -	}
> -#endif
> -	seq_printf(p, "%*s: %10u\n", prec, "ERR", atomic_read(&irq_err_count));
> -#if defined(CONFIG_X86_IO_APIC)
> -	seq_printf(p, "%*s: %10u\n", prec, "MIS", atomic_read(&irq_mis_count));
> +	ITS(HYPERV_REENLIGHTENMENT,	"HRE", " Hyper-V reenlightment interrupts\n"),

There's still a typo in the description string:

s/reenlightment/reenlightenment/

Michael

> +	ITS(HYPERV_STIMER0,		"HVS", " Hyper-V stimer0 interrupts\n"),
>  #endif