On Fri, Feb 20, 2026 at 5:28 PM Jisheng Zhang <[email protected]> wrote: > > Currently, on GENERIC_IRQ_MULTI_HANDLER platforms, the handle_arch_irq > is a pointer which is set during booting, and every irq processing needs > to access it, so it sits in hot code path. We can use the > runtime constant mechanism which was introduced by Linus to speed up > its accessing. > > Tested on Sipeed Lichee Pi 4A (riscv64) board, the perf sched benchmark is > improved by ~5.8% Thx for the work. It's a visible improvement.
Compared to the original handler pointer approach, this solution introduces no observable drawbacks. Since the static_call alternative requires further analysis and consensus, adopting this implementation serves as a pragmatic interim step. So, I give: Reviewed-by: Guo Ren (Alibaba Damo Academy) <[email protected]> > > Signed-off-by: Jisheng Zhang <[email protected]> > --- > include/linux/irq.h | 4 +++- > kernel/irq/handle.c | 8 +++++--- > 2 files changed, 8 insertions(+), 4 deletions(-) > > diff --git a/include/linux/irq.h b/include/linux/irq.h > index 951acbdb9f84..2ba4a8afb71e 100644 > --- a/include/linux/irq.h > +++ b/include/linux/irq.h > @@ -1274,6 +1274,7 @@ void ipi_mux_process(void); > int ipi_mux_create(unsigned int nr_ipi, void (*mux_send)(unsigned int cpu)); > > #ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER > +#include <asm/runtime-const.h> > /* > * Registers a generic IRQ handling function as the top-level IRQ handler in > * the system, which is generally the first C code called from an assembly > @@ -1288,7 +1289,8 @@ int __init set_handle_irq(void (*handle_irq)(struct > pt_regs *)); > * Allows interrupt handlers to find the irqchip that's been registered as > the > * top-level IRQ handler. > */ > -extern void (*handle_arch_irq)(struct pt_regs *) __ro_after_init; > +extern void (*_handle_arch_irq)(struct pt_regs *) __ro_after_init; > +#define handle_arch_irq runtime_const_ptr(_handle_arch_irq) > asmlinkage void generic_handle_arch_irq(struct pt_regs *regs); > #else > #ifndef set_handle_irq > diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c > index b7d52821837b..aac9e7b1301e 100644 > --- a/kernel/irq/handle.c > +++ b/kernel/irq/handle.c > @@ -15,13 +15,14 @@ > #include <linux/kernel_stat.h> > > #include <asm/irq_regs.h> > +#include <asm/runtime-const.h> > > #include <trace/events/irq.h> > > #include "internals.h" > > #ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER > -void (*handle_arch_irq)(struct pt_regs *) __ro_after_init; > +void (*_handle_arch_irq)(struct pt_regs *) __ro_after_init; > #endif > > /** > @@ -270,10 +271,11 @@ irqreturn_t handle_irq_event(struct irq_desc *desc) > #ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER > int __init set_handle_irq(void (*handle_irq)(struct pt_regs *)) > { > - if (handle_arch_irq) > + if (_handle_arch_irq) > return -EBUSY; > > - handle_arch_irq = handle_irq; > + _handle_arch_irq = handle_irq; > + runtime_const_init(ptr, _handle_arch_irq); > return 0; > } > > -- > 2.51.0 > -- Best Regards Guo Ren
