# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID be05097d5d69925a72405201140df8da4c1cfa5c
# Parent ddc25d4ebf6023dba9c49597f3b39fe3f5dc9f0d
[LINUX] Fix IRQ SMP affinity logic for event channels.
The logic now mimics native x86 behaviour: a request to change
affinity via /proc is held until the next interrupt on that
event channel. So /proc/irq/n/smp_affinity may not change
immediately!
Other notes:
1. CPU-specific interrupts silently ignore requests to change
affinity. For example, resched0, timer0, callfunc0, ...
2. Reading smp_affinity always returns a cpumask containing
a single cpu. An event channel can only be bound to a single
cpu at a time. Neither Xen nor XenLinux implement IRQ
balancing: requires a user-space balancing daemon.
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
linux-2.6-xen-sparse/drivers/xen/core/evtchn.c | 47 ++++++++-----------------
1 files changed, 16 insertions(+), 31 deletions(-)
diff -r ddc25d4ebf60 -r be05097d5d69
linux-2.6-xen-sparse/drivers/xen/core/evtchn.c
--- a/linux-2.6-xen-sparse/drivers/xen/core/evtchn.c Sat Jun 10 11:07:11
2006 +0100
+++ b/linux-2.6-xen-sparse/drivers/xen/core/evtchn.c Sun Jun 11 09:54:35
2006 +0100
@@ -54,7 +54,8 @@ static DEFINE_SPINLOCK(irq_mapping_updat
static DEFINE_SPINLOCK(irq_mapping_update_lock);
/* IRQ <-> event-channel mappings. */
-static int evtchn_to_irq[NR_EVENT_CHANNELS] = {[0 ... NR_EVENT_CHANNELS-1] =
-1};
+static int evtchn_to_irq[NR_EVENT_CHANNELS] = {
+ [0 ... NR_EVENT_CHANNELS-1] = -1 };
/* Packed IRQ information: binding type, sub-type index, and event channel. */
static u32 irq_info[NR_IRQS];
@@ -120,6 +121,11 @@ static inline unsigned long active_evtch
static void bind_evtchn_to_cpu(unsigned int chn, unsigned int cpu)
{
+ int irq = evtchn_to_irq[chn];
+
+ BUG_ON(irq == -1);
+ set_native_irq_info(irq, cpumask_of_cpu(cpu));
+
clear_bit(chn, (unsigned long *)cpu_evtchn_mask[cpu_evtchn[chn]]);
set_bit(chn, (unsigned long *)cpu_evtchn_mask[cpu]);
cpu_evtchn[chn] = cpu;
@@ -127,7 +133,12 @@ static void bind_evtchn_to_cpu(unsigned
static void init_evtchn_cpu_bindings(void)
{
+ int i;
+
/* By default all event channels notify CPU#0. */
+ for (i = 0; i < NR_IRQS; i++)
+ set_native_irq_info(i, cpumask_of_cpu(0));
+
memset(cpu_evtchn, 0, sizeof(cpu_evtchn));
memset(cpu_evtchn_mask[0], ~0, sizeof(cpu_evtchn_mask[0]));
}
@@ -430,25 +441,14 @@ void unbind_from_irqhandler(unsigned int
}
EXPORT_SYMBOL_GPL(unbind_from_irqhandler);
-#ifdef CONFIG_SMP
-static void do_nothing_function(void *ign)
-{
-}
-#endif
-
/* Rebind an evtchn so that it gets delivered to a specific cpu */
static void rebind_irq_to_cpu(unsigned irq, unsigned tcpu)
{
struct evtchn_bind_vcpu bind_vcpu;
- int evtchn;
-
- spin_lock(&irq_mapping_update_lock);
-
- evtchn = evtchn_from_irq(irq);
- if (!VALID_EVTCHN(evtchn)) {
- spin_unlock(&irq_mapping_update_lock);
+ int evtchn = evtchn_from_irq(irq);
+
+ if (!VALID_EVTCHN(evtchn))
return;
- }
/* Send future instances of this interrupt to other vcpu. */
bind_vcpu.port = evtchn;
@@ -461,21 +461,6 @@ static void rebind_irq_to_cpu(unsigned i
*/
if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_vcpu, &bind_vcpu) >= 0)
bind_evtchn_to_cpu(evtchn, tcpu);
-
- spin_unlock(&irq_mapping_update_lock);
-
- /*
- * Now send the new target processor a NOP IPI. When this returns, it
- * will check for any pending interrupts, and so service any that got
- * delivered to the wrong processor by mistake.
- *
- * XXX: The only time this is called with interrupts disabled is from
- * the hotplug/hotunplug path. In that case, all cpus are stopped with
- * interrupts disabled, and the missed interrupts will be picked up
- * when they start again. This is kind of a hack.
- */
- if (!irqs_disabled())
- smp_call_function(do_nothing_function, NULL, 0, 0);
}
@@ -597,8 +582,8 @@ static unsigned int startup_pirq(unsigne
pirq_query_unmask(irq_to_pirq(irq));
+ evtchn_to_irq[evtchn] = irq;
bind_evtchn_to_cpu(evtchn, 0);
- evtchn_to_irq[evtchn] = irq;
irq_info[irq] = mk_irq_info(IRQT_PIRQ, irq, evtchn);
out:
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