Do pmap update only on active CPUs.

The pmap update_page/invalidate_page/invalidate_all operations has to be
done only on active cpus. In the simplest case, if the process is not
active on any other CPUs, we can just do the operation on the current CPU.

This change replaces the call to smp_rendezvous() for these operations with
smp_rendezvous_cpus() in case there more than one active CPU, or with a direct
function call if there is just one active CPU.

This change give significant performance increase in fork/exec benchmarks
on XLR/XLS/XLP with 32 cpus.

Reviewed by:	alc

1 files changed, 64 insertions, 98 deletions

diff --git a/sys/mips/mips/pmap.c b/sys/mips/mips/pmap.c
index ec0241e..fc99035 100644
--- a/sys/mips/mips/pmap.c
+++ b/sys/mips/mips/pmap.c
@@ -181,7 +181,6 @@ static pt_entry_t init_pte_prot(vm_offset_t va, vm_page_t m, vm_prot_t prot);
 
 #ifdef SMP
 static void pmap_invalidate_page_action(void *arg);
-static void pmap_invalidate_all_action(void *arg);
 static void pmap_update_page_action(void *arg);
 #endif
 
@@ -622,119 +621,94 @@ pmap_init(void)
  * Low level helper routines.....
  ***************************************************/
 
+#ifdef	SMP
 static __inline void
-pmap_invalidate_all_local(pmap_t pmap)
+pmap_call_on_active_cpus(pmap_t pmap, void (*fn)(void *), void *arg)
 {
-	u_int cpuid;
+	int	cpuid, cpu, self;
+	cpuset_t active_cpus;
 
+	sched_pin();
+	if (is_kernel_pmap(pmap)) {
+		smp_rendezvous(NULL, fn, NULL, arg);
+		goto out;
+	}
+	/* Force ASID update on inactive CPUs */
+	CPU_FOREACH(cpu) {
+		if (!CPU_ISSET(cpu, &pmap->pm_active))
+			pmap->pm_asid[cpu].gen = 0;
+	}
 	cpuid = PCPU_GET(cpuid);
+	/* 
+	 * XXX: barrier/locking for active? 
+	 *
+	 * Take a snapshot of active here, any further changes are ignored.
+	 * tlb update/invalidate should be harmless on inactive CPUs
+	 */
+	active_cpus = pmap->pm_active;
+	self = CPU_ISSET(cpuid, &active_cpus);
+	CPU_CLR(cpuid, &active_cpus);
+	/* Optimize for the case where this cpu is the only active one */
+	if (CPU_EMPTY(&active_cpus)) {
+		if (self)
+			fn(arg);
+	} else {
+		if (self)
+			CPU_SET(cpuid, &active_cpus);
+		smp_rendezvous_cpus(active_cpus, NULL, fn, NULL, arg);
+	}
+out:
+	sched_unpin();
+}
+#else /* !SMP */
+static __inline void
+pmap_call_on_active_cpus(pmap_t pmap, void (*fn)(void *), void *arg)
+{
+	int	cpuid;
 
-	if (pmap == kernel_pmap) {
-		tlb_invalidate_all();
+	if (is_kernel_pmap(pmap)) {
+		fn(arg);
 		return;
 	}
-	if (CPU_ISSET(cpuid, &pmap->pm_active))
-		tlb_invalidate_all_user(pmap);
-	else
+	cpuid = PCPU_GET(cpuid);
+	if (!CPU_ISSET(cpuid, &pmap->pm_active))
 		pmap->pm_asid[cpuid].gen = 0;
+	else
+		fn(arg);
 }
+#endif /* SMP */
 
-#ifdef SMP
 static void
 pmap_invalidate_all(pmap_t pmap)
 {
 
-	smp_rendezvous(0, pmap_invalidate_all_action, 0, pmap);
+	pmap_call_on_active_cpus(pmap,
+	    (void (*)(void *))tlb_invalidate_all_user, pmap);
 }
 
-static void
-pmap_invalidate_all_action(void *arg)
-{
-
-	pmap_invalidate_all_local((pmap_t)arg);
-}
-#else
-static void
-pmap_invalidate_all(pmap_t pmap)
-{
-
-	pmap_invalidate_all_local(pmap);
-}
-#endif
-
-static __inline void
-pmap_invalidate_page_local(pmap_t pmap, vm_offset_t va)
-{
-	u_int cpuid;
-
-	cpuid = PCPU_GET(cpuid);
-
-	if (is_kernel_pmap(pmap)) {
-		tlb_invalidate_address(pmap, va);
-		return;
-	}
-	if (pmap->pm_asid[cpuid].gen != PCPU_GET(asid_generation))
-		return;
-	else if (!CPU_ISSET(cpuid, &pmap->pm_active)) {
-		pmap->pm_asid[cpuid].gen = 0;
-		return;
-	}
-	tlb_invalidate_address(pmap, va);
-}
-
-#ifdef SMP
 struct pmap_invalidate_page_arg {
 	pmap_t pmap;
 	vm_offset_t va;
 };
 
 static void
-pmap_invalidate_page(pmap_t pmap, vm_offset_t va)
-{
-	struct pmap_invalidate_page_arg arg;
-
-	arg.pmap = pmap;
-	arg.va = va;
-	smp_rendezvous(0, pmap_invalidate_page_action, 0, &arg);
-}
-
-static void
 pmap_invalidate_page_action(void *arg)
 {
 	struct pmap_invalidate_page_arg *p = arg;
 
-	pmap_invalidate_page_local(p->pmap, p->va);
+	tlb_invalidate_address(p->pmap, p->va);
 }
-#else
+
 static void
 pmap_invalidate_page(pmap_t pmap, vm_offset_t va)
 {
+	struct pmap_invalidate_page_arg arg;
 
-	pmap_invalidate_page_local(pmap, va);
-}
-#endif
-
-static __inline void
-pmap_update_page_local(pmap_t pmap, vm_offset_t va, pt_entry_t pte)
-{
-	u_int cpuid;
-
-	cpuid = PCPU_GET(cpuid);
-
-	if (is_kernel_pmap(pmap)) {
-		tlb_update(pmap, va, pte);
-		return;
-	}
-	if (pmap->pm_asid[cpuid].gen != PCPU_GET(asid_generation))
-		return;
-	else if (!CPU_ISSET(cpuid, &pmap->pm_active)) {
-		pmap->pm_asid[cpuid].gen = 0;
-		return;
-	}
-	tlb_update(pmap, va, pte);
+	arg.pmap = pmap;
+	arg.va = va;
+	pmap_call_on_active_cpus(pmap, pmap_invalidate_page_action, &arg);
 }
 
-#ifdef SMP
 struct pmap_update_page_arg {
 	pmap_t pmap;
 	vm_offset_t va;
@@ -742,31 +716,23 @@ struct pmap_update_page_arg {
 };
 
 static void
-pmap_update_page(pmap_t pmap, vm_offset_t va, pt_entry_t pte)
-{
-	struct pmap_update_page_arg arg;
-
-	arg.pmap = pmap;
-	arg.va = va;
-	arg.pte = pte;
-	smp_rendezvous(0, pmap_update_page_action, 0, &arg);
-}
-
-static void
 pmap_update_page_action(void *arg)
 {
 	struct pmap_update_page_arg *p = arg;
 
-	pmap_update_page_local(p->pmap, p->va, p->pte);
+	tlb_update(p->pmap, p->va, p->pte);
 }
-#else
+
 static void
 pmap_update_page(pmap_t pmap, vm_offset_t va, pt_entry_t pte)
 {
+	struct pmap_update_page_arg arg;
 
-	pmap_update_page_local(pmap, va, pte);
+	arg.pmap = pmap;
+	arg.va = va;
+	arg.pte = pte;
+	pmap_call_on_active_cpus(pmap, pmap_update_page_action, &arg);
 }
-#endif
 
 /*
  *	Routine:	pmap_extract
@@ -3213,7 +3179,7 @@ pmap_emulate_modified(pmap_t pmap, vm_offset_t va)
 #ifdef SMP
 	/* It is possible that some other CPU changed m-bit */
 	if (!pte_test(pte, PTE_V) || pte_test(pte, PTE_D)) {
-		pmap_update_page_local(pmap, va, *pte);
+		tlb_update(pmap, va, *pte);
 		PMAP_UNLOCK(pmap);
 		return (0);
 	}
@@ -3227,7 +3193,7 @@ pmap_emulate_modified(pmap_t pmap, vm_offset_t va)
 		return (1);
 	}
 	pte_set(pte, PTE_D);
-	pmap_update_page_local(pmap, va, *pte);
+	tlb_update(pmap, va, *pte);
 	pa = TLBLO_PTE_TO_PA(*pte);
 	if (!page_is_managed(pa))
 		panic("pmap_emulate_modified: unmanaged page");