[PATCH] x86-64: Make remote TLB flush more scalable

Instead of using a global spinlock to protect the state
of the remote TLB flush use a lock and state for each sending CPU.

To tell the receiver where to look for the state use 8 different
call vectors.  Each CPU uses a specific vector to trigger flushes on other
CPUs. Depending on the received vector the target CPUs look into
the right per cpu variable for the flush data.

When the system has more than 8 CPUs they are hashed to the 8 available
vectors. The limited global vector space forces us to this right now.
In future when interrupts are split into per CPU domains this could be
fixed, at the cost of needing more IPIs in flat mode.

Also some minor cleanup in the smp flush code and remove some outdated
debug code.

Requires patch to move cpu_possible_map setup earlier.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 9 insertions, 8 deletions

diff --git a/include/asm-x86_64/hw_irq.h b/include/asm-x86_64/hw_irq.h
index 2b5cb2865d21..d9212eb4e894 100644
--- a/include/asm-x86_64/hw_irq.h
+++ b/include/asm-x86_64/hw_irq.h
@@ -50,14 +50,15 @@ struct hw_interrupt_type;
  */
 #define SPURIOUS_APIC_VECTOR    0xff
 #define ERROR_APIC_VECTOR       0xfe
-#define INVALIDATE_TLB_VECTOR   0xfd
-#define RESCHEDULE_VECTOR       0xfc
-#define TASK_MIGRATION_VECTOR   0xfb
-#define CALL_FUNCTION_VECTOR    0xfa
-#define KDB_VECTOR      0xf9
-
-#define THERMAL_APIC_VECTOR     0xf0
-
+#define RESCHEDULE_VECTOR       0xfd
+#define CALL_FUNCTION_VECTOR    0xfc
+#define KDB_VECTOR              0xfb    /* reserved for KDB */
+#define THERMAL_APIC_VECTOR     0xfa
+/* 0xf9 free */
+#define INVALIDATE_TLB_VECTOR_END       0xf8
+#define INVALIDATE_TLB_VECTOR_START     0xf0    /* f0-f8 used for TLB flush */
+
+#define NUM_INVALIDATE_TLB_VECTORS      8
 
 /*
  * Local APIC timer IRQ vector is on a different priority level,