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authorH. Peter Anvin <hpa@zytor.com>2010-01-04 21:14:41 -0800
committerH. Peter Anvin <hpa@zytor.com>2010-01-04 21:28:24 -0800
commitea94396629a3e0cb9a3a9c75335b1de255b30426 (patch)
tree32208d082a54a3069170195c1d046e95620ebd8f /arch/x86/kernel/apic
parent99d113b17e8ca5a8b68a9d3f7691e2f552dd6a06 (diff)
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 <hpa@zytor.com> LKML-Reference: <4B426550.6000209@kernel.org>
Diffstat (limited to 'arch/x86/kernel/apic')
-rw-r--r--arch/x86/kernel/apic/io_apic.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index d9cd1f1b9c0..e9ba0903e9d 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -1162,7 +1162,8 @@ __assign_irq_vector(int irq, struct irq_cfg *cfg, const struct cpumask *mask)
* Also, we've got to be careful not to trash gate
* 0x80, because int 0x80 is hm, kind of importantish. ;)
*/
- static int current_vector = FIRST_DEVICE_VECTOR, current_offset = 0;
+ static int current_vector = FIRST_DEVICE_VECTOR + VECTOR_OFFSET_START;
+ static int current_offset = VECTOR_OFFSET_START % 8;
unsigned int old_vector;
int cpu, err;
cpumask_var_t tmp_mask;