Currently, on GENERIC_IRQ_MULTI_HANDLER or arm64 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% Tested on Quad CA55 platform, the perf sched benchmark is improved by ~6.5% As for the GENERIC_IRQ_MULTI_HANDLER platforms but without runtime const support, such as arm, csky, loongarch, microblaze and openrisc, there should be no changes. Jisheng Zhang (3): vmlinux.lds.h: add _handle_arch_irq RUNTIME_CONST section genirq: use runtime constant to optimize handle_arch_irq access arm64: use runtime constant to optimize handle_arch_irq access arch/arm64/kernel/entry-common.c | 4 +++- arch/arm64/kernel/irq.c | 9 ++++++--- include/asm-generic/vmlinux.lds.h | 3 ++- include/linux/irq.h | 4 +++- kernel/irq/handle.c | 8 +++++--- 5 files changed, 19 insertions(+), 9 deletions(-) -- 2.51.0
