1 files changed, 78 insertions, 45 deletions

diff --git a/arch/x86_64/kernel/smp.c b/arch/x86_64/kernel/smp.c
index 82d38f145b43..801db885955c 100644
--- a/arch/x86_64/kernel/smp.c
+++ b/arch/x86_64/kernel/smp.c
@@ -29,6 +29,8 @@
 #include <asm/proto.h>
 #include <asm/apicdef.h>
 
+#define __cpuinit __init
+
 /*
  *      Smarter SMP flushing macros. 
  *              c/o Linus Torvalds.
@@ -37,19 +39,41 @@
  *      writing to user space from interrupts. (Its not allowed anyway).
  *
  *      Optimizations Manfred Spraul <manfred@colorfullife.com>
+ *
+ *      More scalable flush, from Andi Kleen
+ *
+ *      To avoid global 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.
+ *
+ *      With 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 triggering multiple IPIs in some cases.
  */
 
-static cpumask_t flush_cpumask;
-static struct mm_struct * flush_mm;
-static unsigned long flush_va;
-static DEFINE_SPINLOCK(tlbstate_lock);
+union smp_flush_state {
+        struct {
+                cpumask_t flush_cpumask;
+                struct mm_struct *flush_mm;
+                unsigned long flush_va;
 #define FLUSH_ALL       -1ULL
+                spinlock_t tlbstate_lock;
+        };
+        char pad[SMP_CACHE_BYTES];
+} ____cacheline_aligned;
+
+/* State is put into the per CPU data section, but padded
+   to a full cache line because other CPUs can access it and we don't
+   want false sharing in the per cpu data segment. */
+static DEFINE_PER_CPU(union smp_flush_state, flush_state);
 
 /*
  * We cannot call mmdrop() because we are in interrupt context, 
  * instead update mm->cpu_vm_mask.
  */
-static inline void leave_mm (unsigned long cpu)
+static inline void leave_mm(int cpu)
 {
         if (read_pda(mmu_state) == TLBSTATE_OK)
                 BUG();
@@ -101,15 +125,25 @@ static inline void leave_mm (unsigned long cpu)
  *
  * 1) Flush the tlb entries if the cpu uses the mm that's being flushed.
  * 2) Leave the mm if we are in the lazy tlb mode.
+ *
+ * Interrupts are disabled.
  */
 
-asmlinkage void smp_invalidate_interrupt (void)
+asmlinkage void smp_invalidate_interrupt(struct pt_regs *regs)
 {
-        unsigned long cpu;
+        int cpu;
+        int sender;
+        union smp_flush_state *f;
 
-        cpu = get_cpu();
+        cpu = smp_processor_id();
+        /*
+         * orig_rax contains the interrupt vector - 256.
+         * Use that to determine where the sender put the data.
+         */
+        sender = regs->orig_rax + 256 - INVALIDATE_TLB_VECTOR_START;
+        f = &per_cpu(flush_state, sender);
 
-        if (!cpu_isset(cpu, flush_cpumask))
+        if (!cpu_isset(cpu, f->flush_cpumask))
                 goto out;
                 /* 
                  * This was a BUG() but until someone can quote me the
@@ -120,64 +154,63 @@ asmlinkage void smp_invalidate_interrupt (void)
                  * BUG();
                  */
                  
-        if (flush_mm == read_pda(active_mm)) {
+        if (f->flush_mm == read_pda(active_mm)) {
                 if (read_pda(mmu_state) == TLBSTATE_OK) {
-                        if (flush_va == FLUSH_ALL)
+                        if (f->flush_va == FLUSH_ALL)
                                 local_flush_tlb();
                         else
-                                __flush_tlb_one(flush_va);
+                                __flush_tlb_one(f->flush_va);
                 } else
                         leave_mm(cpu);
         }
 out:
         ack_APIC_irq();
-        cpu_clear(cpu, flush_cpumask);
-        put_cpu_no_resched();
+        cpu_clear(cpu, f->flush_cpumask);
 }
 
 static void flush_tlb_others(cpumask_t cpumask, struct mm_struct *mm,
                                                 unsigned long va)
 {
-        cpumask_t tmp;
-        /*
-         * A couple of (to be removed) sanity checks:
-         *
-         * - we do not send IPIs to not-yet booted CPUs.
-         * - current CPU must not be in mask
-         * - mask must exist :)
-         */
-        BUG_ON(cpus_empty(cpumask));
-        cpus_and(tmp, cpumask, cpu_online_map);
-        BUG_ON(!cpus_equal(tmp, cpumask));
-        BUG_ON(cpu_isset(smp_processor_id(), cpumask));
-        if (!mm)
-                BUG();
+        int sender;
+        union smp_flush_state *f;
 
-        /*
-         * I'm not happy about this global shared spinlock in the
-         * MM hot path, but we'll see how contended it is.
-         * Temporarily this turns IRQs off, so that lockups are
-         * detected by the NMI watchdog.
-         */
-        spin_lock(&tlbstate_lock);
-        
-        flush_mm = mm;
-        flush_va = va;
-        cpus_or(flush_cpumask, cpumask, flush_cpumask);
+        /* Caller has disabled preemption */
+        sender = smp_processor_id() % NUM_INVALIDATE_TLB_VECTORS;
+        f = &per_cpu(flush_state, sender);
+
+        /* Could avoid this lock when
+           num_online_cpus() <= NUM_INVALIDATE_TLB_VECTORS, but it is
+           probably not worth checking this for a cache-hot lock. */
+        spin_lock(&f->tlbstate_lock);
+
+        f->flush_mm = mm;
+        f->flush_va = va;
+        cpus_or(f->flush_cpumask, cpumask, f->flush_cpumask);
 
         /*
          * We have to send the IPI only to
          * CPUs affected.
          */
-        send_IPI_mask(cpumask, INVALIDATE_TLB_VECTOR);
+        send_IPI_mask(cpumask, INVALIDATE_TLB_VECTOR_START + sender);
 
-        while (!cpus_empty(flush_cpumask))
-                mb();   /* nothing. lockup detection does not belong here */;
+        while (!cpus_empty(f->flush_cpumask))
+                cpu_relax();
 
-        flush_mm = NULL;
-        flush_va = 0;
-        spin_unlock(&tlbstate_lock);
+        f->flush_mm = NULL;
+        f->flush_va = 0;
+        spin_unlock(&f->tlbstate_lock);
 }
+
+int __cpuinit init_smp_flush(void)
+{
+        int i;
+        for_each_cpu_mask(i, cpu_possible_map) {
+                spin_lock_init(&per_cpu(flush_state.tlbstate_lock, i));
+        }
+        return 0;
+}
+
+core_initcall(init_smp_flush);
         
 void flush_tlb_current_task(void)
 {