From ea94396629a3e0cb9a3a9c75335b1de255b30426 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Mon, 4 Jan 2010 21:14:41 -0800 Subject: x86, apic: Don't waste a vector to improve vector spread We want to use a vector-assignment sequence that avoids stumbling onto 0x80 earlier in the sequence, in order to improve the spread of vectors across priority levels on machines with a small number of interrupt sources. Right now, this is done by simply making the first vector (0x31 or 0x41) completely unusable. This is unnecessary; all we need is to start assignment at a +1 offset, we don't actually need to prohibit the usage of this vector once we have wrapped around. Signed-off-by: H. Peter Anvin LKML-Reference: <4B426550.6000209@kernel.org> --- arch/x86/include/asm/irq_vectors.h | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'arch/x86/include/asm/irq_vectors.h') diff --git a/arch/x86/include/asm/irq_vectors.h b/arch/x86/include/asm/irq_vectors.h index dbc81ac..585a428 100644 --- a/arch/x86/include/asm/irq_vectors.h +++ b/arch/x86/include/asm/irq_vectors.h @@ -133,11 +133,12 @@ #define MCE_SELF_VECTOR 0xeb /* - * First APIC vector available to drivers: (vectors 0x30-0xee) we - * start at 0x31 to spread out vectors evenly between priority - * levels. (0x80 is the syscall vector) + * First APIC vector available to drivers: (vectors 0x30-0xee). We + * start allocating at 0x31 to spread out vectors evenly between + * priority levels. (0x80 is the syscall vector) */ -#define FIRST_DEVICE_VECTOR (IRQ15_VECTOR + 2) +#define FIRST_DEVICE_VECTOR (IRQ15_VECTOR + 1) +#define VECTOR_OFFSET_START 1 #define NR_VECTORS 256 -- cgit v1.1