The patch titled
x86_64 irq: reuse vector for __assign_irq_vector
has been added to the -mm tree. Its filename is
x86_64-irq-reuse-vector-for-__assign_irq_vector.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: x86_64 irq: reuse vector for __assign_irq_vector
From: "Yinghai Lu" <yinghai.lu@xxxxxxx>
In phys flat mode, when using set_xxx_irq_affinity to irq balance from one
cpu to another, _assign_irq_vector will get to increase last used vector
and get new vector. this will use up the vector if enough
set_xxx_irq_affintiy are called. and end with using same vector in want to
use same vector in different cpu for different irq when more than 0x240 irq
needed). To keep it simple, the vector should be reused instead of getting
new vector.
Also according to Eric's review, make it more generic to be used with
flat mode too.
It also check if new domain and old domain is equal, to avoid extra
operation.
Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Muli Ben-Yehuda <muli@xxxxxxxxxx>
Signed-off-by: Yinghai Lu <yinghai.lu@xxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
arch/x86_64/kernel/io_apic.c | 72 +++++++++++++++++++++++----------
1 files changed, 51 insertions(+), 21 deletions(-)
diff -puN arch/x86_64/kernel/io_apic.c~x86_64-irq-reuse-vector-for-__assign_irq_vector arch/x86_64/kernel/io_apic.c
--- a/arch/x86_64/kernel/io_apic.c~x86_64-irq-reuse-vector-for-__assign_irq_vector
+++ a/arch/x86_64/kernel/io_apic.c
@@ -613,8 +613,9 @@ static int __assign_irq_vector(int irq,
* 0x80, because int 0x80 is hm, kind of importantish. ;)
*/
static int current_vector = FIRST_DEVICE_VECTOR, current_offset = 0;
- int old_vector = -1;
- int cpu;
+ int vector = -1, old_vector = -1;
+ cpumask_t domain, new_mask;
+ int cpu, new_cpu;
BUG_ON((unsigned)irq >= NR_IRQ_VECTORS);
@@ -624,15 +625,38 @@ static int __assign_irq_vector(int irq,
if (irq_vector[irq] > 0)
old_vector = irq_vector[irq];
if (old_vector > 0) {
- cpus_and(*result, irq_domain[irq], mask);
- if (!cpus_empty(*result))
- return old_vector;
+ /* try to reuse vector */
+ for_each_cpu_mask(cpu, mask) {
+ int can_reuse = 1;
+
+ domain = vector_allocation_domain(cpu);
+ cpus_and(new_mask, domain, cpu_online_map);
+
+ if (cpus_equal(domain, irq_domain[irq])) {
+ cpus_and(*result, irq_domain[irq], mask);
+ if (!cpus_empty(*result))
+ return old_vector;
+ }
+
+ for_each_cpu_mask(new_cpu, new_mask) {
+ int old_irq;
+ old_irq = per_cpu(vector_irq, new_cpu)[old_vector];
+ if ((old_irq != irq) && (old_irq != -1)) {
+ can_reuse = 0;
+ break;
+ }
+ }
+
+ if(!can_reuse)
+ continue;
+
+ vector = old_vector;
+ goto found_one;
+ }
}
for_each_cpu_mask(cpu, mask) {
- cpumask_t domain, new_mask;
- int new_cpu;
- int vector, offset;
+ int offset;
domain = vector_allocation_domain(cpu);
cpus_and(new_mask, domain, cpu_online_map);
@@ -656,21 +680,27 @@ next:
/* Found one! */
current_vector = vector;
current_offset = offset;
- if (old_vector >= 0) {
- cpumask_t old_mask;
- int old_cpu;
- cpus_and(old_mask, irq_domain[irq], cpu_online_map);
- for_each_cpu_mask(old_cpu, old_mask)
- per_cpu(vector_irq, old_cpu)[old_vector] = -1;
- }
- for_each_cpu_mask(new_cpu, new_mask)
- per_cpu(vector_irq, new_cpu)[vector] = irq;
- irq_vector[irq] = vector;
- irq_domain[irq] = domain;
- cpus_and(*result, domain, mask);
- return vector;
+
+ goto found_one;
}
+
return -ENOSPC;
+
+found_one:
+ if (old_vector >= 0) {
+ cpumask_t old_mask;
+ int old_cpu;
+ cpus_and(old_mask, irq_domain[irq], cpu_online_map);
+ for_each_cpu_mask(old_cpu, old_mask)
+ per_cpu(vector_irq, old_cpu)[old_vector] = -1;
+ }
+ for_each_cpu_mask(new_cpu, new_mask)
+ per_cpu(vector_irq, new_cpu)[vector] = irq;
+ irq_vector[irq] = vector;
+ irq_domain[irq] = domain;
+ cpus_and(*result, domain, mask);
+ return vector;
+
}
static int assign_irq_vector(int irq, cpumask_t mask, cpumask_t *result)
_
Patches currently in -mm which might be from yinghai.lu@xxxxxxx are
x86_64-irq-reuse-vector-for-__assign_irq_vector.patch
-
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