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authorZhang Yanmin <yanmin.zhang@intel.com>2006-06-23 02:04:22 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-23 07:42:57 -0700
commit1b61b910e99059abdd54c93aa70e84e076e33d16 (patch)
treefe2cd431dc39521a0f2d30e22c9bd3eb3e1bc317 /arch/i386
parentafa024c3dbccf026e45121f4b9de54cda48edbea (diff)
downloadblackbird-op-linux-1b61b910e99059abdd54c93aa70e84e076e33d16.tar.gz
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[PATCH] x86: kernel irq balance doesn't work
On i386, kernel irq balance doesn't work. 1) In function do_irq_balance, after kernel finds the min_loaded cpu but before calling set_pending_irq to really pin the selected_irq to the target cpu, kernel does a cpus_and with irq_affinity[selected_irq]. Later on, when the irq is acked, kernel would calls move_native_irq=>desc->handler->set_affinity to change the irq affinity. However, every function pointed by hw_interrupt_type->set_affinity(unsigned int irq, cpumask_t cpumask) always changes irq_affinity[irq] to cpumask. Next time when recalling do_irq_balance, it has to do cpu_ands again with irq_affinity[selected_irq], but irq_affinity[selected_irq] already becomes one cpu selected by the first irq balance. 2) Function balance_irq in file arch/i386/kernel/io_apic.c has the same issue. [akpm@osdl.org: cleanups] Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/i386')
-rw-r--r--arch/i386/kernel/io_apic.c31
1 files changed, 20 insertions, 11 deletions
diff --git a/arch/i386/kernel/io_apic.c b/arch/i386/kernel/io_apic.c
index d70f2ade5cde..a62df3e764c5 100644
--- a/arch/i386/kernel/io_apic.c
+++ b/arch/i386/kernel/io_apic.c
@@ -267,7 +267,7 @@ static void set_ioapic_affinity_irq(unsigned int irq, cpumask_t cpumask)
# include <linux/slab.h> /* kmalloc() */
# include <linux/timer.h> /* time_after() */
-# ifdef CONFIG_BALANCED_IRQ_DEBUG
+#ifdef CONFIG_BALANCED_IRQ_DEBUG
# define TDprintk(x...) do { printk("<%ld:%s:%d>: ", jiffies, __FILE__, __LINE__); printk(x); } while (0)
# define Dprintk(x...) do { TDprintk(x); } while (0)
# else
@@ -275,10 +275,15 @@ static void set_ioapic_affinity_irq(unsigned int irq, cpumask_t cpumask)
# define Dprintk(x...)
# endif
-
#define IRQBALANCE_CHECK_ARCH -999
-static int irqbalance_disabled = IRQBALANCE_CHECK_ARCH;
-static int physical_balance = 0;
+#define MAX_BALANCED_IRQ_INTERVAL (5*HZ)
+#define MIN_BALANCED_IRQ_INTERVAL (HZ/2)
+#define BALANCED_IRQ_MORE_DELTA (HZ/10)
+#define BALANCED_IRQ_LESS_DELTA (HZ)
+
+static int irqbalance_disabled __read_mostly = IRQBALANCE_CHECK_ARCH;
+static int physical_balance __read_mostly;
+static long balanced_irq_interval __read_mostly = MAX_BALANCED_IRQ_INTERVAL;
static struct irq_cpu_info {
unsigned long * last_irq;
@@ -297,12 +302,14 @@ static struct irq_cpu_info {
#define CPU_TO_PACKAGEINDEX(i) (first_cpu(cpu_sibling_map[i]))
-#define MAX_BALANCED_IRQ_INTERVAL (5*HZ)
-#define MIN_BALANCED_IRQ_INTERVAL (HZ/2)
-#define BALANCED_IRQ_MORE_DELTA (HZ/10)
-#define BALANCED_IRQ_LESS_DELTA (HZ)
+static cpumask_t balance_irq_affinity[NR_IRQS] = {
+ [0 ... NR_IRQS-1] = CPU_MASK_ALL
+};
-static long balanced_irq_interval = MAX_BALANCED_IRQ_INTERVAL;
+void set_balance_irq_affinity(unsigned int irq, cpumask_t mask)
+{
+ balance_irq_affinity[irq] = mask;
+}
static unsigned long move(int curr_cpu, cpumask_t allowed_mask,
unsigned long now, int direction)
@@ -340,7 +347,7 @@ static inline void balance_irq(int cpu, int irq)
if (irqbalance_disabled)
return;
- cpus_and(allowed_mask, cpu_online_map, irq_affinity[irq]);
+ cpus_and(allowed_mask, cpu_online_map, balance_irq_affinity[irq]);
new_cpu = move(cpu, allowed_mask, now, 1);
if (cpu != new_cpu) {
set_pending_irq(irq, cpumask_of_cpu(new_cpu));
@@ -529,7 +536,9 @@ tryanotherirq:
}
}
- cpus_and(allowed_mask, cpu_online_map, irq_affinity[selected_irq]);
+ cpus_and(allowed_mask,
+ cpu_online_map,
+ balance_irq_affinity[selected_irq]);
target_cpu_mask = cpumask_of_cpu(min_loaded);
cpus_and(tmp, target_cpu_mask, allowed_mask);
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