From d1752aa884ec0ac3027c1a3d456bf69bf765c8b8 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Wed, 25 Oct 2006 01:00:22 +0200 Subject: [PATCH] [PATCH] x86-64: Simplify the vector allocator. There is no reason to remember a per cpu position of which vector to try. Keeping a global position is simpler and more likely to result in a global vector allocation even if I don't need or require it. For level triggered interrupts this means we are less likely to acknowledge another cpus irq, and cause the level triggered irq to harmlessly refire. This simplification makes it easier to only access data structures of online cpus, by having fewer special cases to deal with. Signed-off-by: Eric W. Biederman Signed-off-by: Andi Kleen --- arch/x86_64/kernel/io_apic.c | 20 +++++++------------- 1 file changed, 7 insertions(+), 13 deletions(-) diff --git a/arch/x86_64/kernel/io_apic.c b/arch/x86_64/kernel/io_apic.c index b000017e4b5d..0e89ae7e7b22 100644 --- a/arch/x86_64/kernel/io_apic.c +++ b/arch/x86_64/kernel/io_apic.c @@ -612,10 +612,7 @@ static int __assign_irq_vector(int irq, cpumask_t mask, cpumask_t *result) * Also, we've got to be careful not to trash gate * 0x80, because int 0x80 is hm, kind of importantish. ;) */ - static struct { - int vector; - int offset; - } pos[NR_CPUS] = { [ 0 ... NR_CPUS - 1] = {FIRST_DEVICE_VECTOR, 0} }; + static int current_vector = FIRST_DEVICE_VECTOR, current_offset = 0; int old_vector = -1; int cpu; @@ -631,14 +628,13 @@ static int __assign_irq_vector(int irq, cpumask_t mask, cpumask_t *result) for_each_cpu_mask(cpu, mask) { cpumask_t domain; - int first, new_cpu; + int new_cpu; int vector, offset; domain = vector_allocation_domain(cpu); - first = first_cpu(domain); - vector = pos[first].vector; - offset = pos[first].offset; + vector = current_vector; + offset = current_offset; next: vector += 8; if (vector >= FIRST_SYSTEM_VECTOR) { @@ -646,7 +642,7 @@ next: offset = (offset + 1) % 8; vector = FIRST_DEVICE_VECTOR + offset; } - if (unlikely(pos[first].vector == vector)) + if (unlikely(current_vector == vector)) continue; if (vector == IA32_SYSCALL_VECTOR) goto next; @@ -654,10 +650,8 @@ next: if (per_cpu(vector_irq, new_cpu)[vector] != -1) goto next; /* Found one! */ - for_each_cpu_mask(new_cpu, domain) { - pos[new_cpu].vector = vector; - pos[new_cpu].offset = offset; - } + current_vector = vector; + current_offset = offset; if (old_vector >= 0) { int old_cpu; for_each_cpu_mask(old_cpu, irq_domain[irq]) -- 2.20.1