From 0ab711ae6ab0db7696b43c74f9ba9de4d7fc1deb Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Wed, 16 May 2012 19:03:58 +0300 Subject: x86/apic: Implement EIO 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. I looked at the objdump output to verify that the generated code looks right and actually is shorter. The real improvemements will be on the KVM guest side though, those come in a later patch. Signed-off-by: Michael S. Tsirkin Cc: Avi Kivity Cc: Marcelo Tosatti Cc: gleb@redhat.com Cc: Linus Torvalds Link: http://lkml.kernel.org/r/e019d1a125316f10d3e3a4b2f6bda41473f4fb72.1337184153.git.mst@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/apic.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'arch/x86/include/asm/apic.h') diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h index bf8d065dd977..eaff4790ed96 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; -- cgit v1.2.3