From 33b3aa018de3309ce6eb1ccf51d5f91db7536fec Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Wed, 18 Apr 2012 12:57:10 +0300 Subject: [PATCH] x86: eoi micro-optimization We know both register and value for eoi beforehand, so there's no need to check it and no need to do math to calculate the msr. Saves instructions/branches on each EOI when using x2apic. Signed-off-by: Michael S. Tsirkin --- arch/x86/include/asm/apic.h | 5 +++++ arch/x86/kernel/apic/x2apic_cluster.c | 2 +- arch/x86/kernel/apic/x2apic_phys.c | 2 +- arch/x86/kernel/apic/x2apic_uv_x.c | 2 +- 4 files changed, 8 insertions(+), 3 deletions(-) diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h index 74efb8df8d7c..5eb6d56ab34e 100644 --- a/arch/x86/include/asm/apic.h +++ b/arch/x86/include/asm/apic.h @@ -138,6 +138,11 @@ static inline void native_apic_msr_write(u32 reg, u32 v) wrmsr(APIC_BASE_MSR + (reg >> 4), v, 0); } +static inline void native_apic_msr_eoi_write(u32 reg, u32 v) +{ + wrmsr(APIC_BASE_MSR + (APIC_EOI >> 4), APIC_EOI_ACK, 0); +} + static inline u32 native_apic_msr_read(u32 reg) { u64 msr; diff --git a/arch/x86/kernel/apic/x2apic_cluster.c b/arch/x86/kernel/apic/x2apic_cluster.c index a5baa785a251..ff35cff0e1a7 100644 --- a/arch/x86/kernel/apic/x2apic_cluster.c +++ b/arch/x86/kernel/apic/x2apic_cluster.c @@ -260,7 +260,7 @@ static struct apic apic_x2apic_cluster = { .read = native_apic_msr_read, .write = native_apic_msr_write, - .eoi_write = native_apic_msr_write, + .eoi_write = native_apic_msr_eoi_write, .icr_read = native_x2apic_icr_read, .icr_write = native_x2apic_icr_write, .wait_icr_idle = native_x2apic_wait_icr_idle, diff --git a/arch/x86/kernel/apic/x2apic_phys.c b/arch/x86/kernel/apic/x2apic_phys.c index aac165b9f1b7..06a08128d33d 100644 --- a/arch/x86/kernel/apic/x2apic_phys.c +++ b/arch/x86/kernel/apic/x2apic_phys.c @@ -166,7 +166,7 @@ static struct apic apic_x2apic_phys = { .read = native_apic_msr_read, .write = native_apic_msr_write, - .eoi_write = native_apic_msr_write, + .eoi_write = native_apic_msr_eoi_write, .icr_read = native_x2apic_icr_read, .icr_write = native_x2apic_icr_write, .wait_icr_idle = native_x2apic_wait_icr_idle, diff --git a/arch/x86/kernel/apic/x2apic_uv_x.c b/arch/x86/kernel/apic/x2apic_uv_x.c index 5b0e3d0a3d2d..c6d03f7a4401 100644 --- a/arch/x86/kernel/apic/x2apic_uv_x.c +++ b/arch/x86/kernel/apic/x2apic_uv_x.c @@ -404,7 +404,7 @@ static struct apic __refdata apic_x2apic_uv_x = { .read = native_apic_msr_read, .write = native_apic_msr_write, - .eoi_write = native_apic_msr_write, + .eoi_write = native_apic_msr_eoi_write, .icr_read = native_x2apic_icr_read, .icr_write = native_x2apic_icr_write, .wait_icr_idle = native_x2apic_wait_icr_idle, -- 2.39.5