[PATH v2 4/5] x86/tlb: add tlb flush all factor for specific CPUs

[Alex Shi]

Testing show different CPU type(micro architectures and NUMA mode) has
different balance points between the TLB flush all and multiple invlpg.
And there maybe has cases the tlb flush change has no any help.

This patch give a interface to let x86 vendor developers have a chance
to set different factors for different CPU type.

like some machine in my hands, balance points is 16 entries on Romely-EP;
while it is at 8 entries on Bloomfield NHM-EP; but on model 15 core2 Xeon
using invlpg has nothing help.

For untested machine, no optimization now.

Signed-off-by: Alex Shi <alex.shi@xxxxxxxxx>
---
 arch/x86/include/asm/processor.h |    2 ++
 arch/x86/kernel/cpu/common.c     |   13 +++++++++++--
 arch/x86/kernel/cpu/intel.c      |   30 ++++++++++++++++++++++++++++++
 arch/x86/mm/tlb.c                |    8 ++++----
 4 files changed, 47 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 797faca..6a7e9c3 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -72,6 +72,8 @@ extern u16 __read_mostly tlb_lli_4m[NR_INFO];
 extern u16 __read_mostly tlb_lld_4k[NR_INFO];
 extern u16 __read_mostly tlb_lld_2m[NR_INFO];
 extern u16 __read_mostly tlb_lld_4m[NR_INFO];
+extern u16 __read_mostly tlb_flushall_factor;
+
 /*
  *  CPU type and hardware bug flags. Kept separately for each CPU.
  *  Members of this structure are referenced in head.S, so think twice
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index d764819..71e7891 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -459,16 +459,25 @@ u16 __read_mostly tlb_lld_4k[NR_INFO];
 u16 __read_mostly tlb_lld_2m[NR_INFO];
 u16 __read_mostly tlb_lld_4m[NR_INFO];
 
+/*
+ * tlb_flushall_factor shows the balance point in replacing cr3 write with
+ * multiple 'invlpg'. Different CPU type has different this value, which
+ * get from a macro benchmark named mproctect.c that published in lkml.
+ */
+u16 __read_mostly tlb_flushall_factor;
+
 void __cpuinit cpu_detect_tlb(struct cpuinfo_x86 *c)
 {
 	if (c->x86_vendor == X86_VENDOR_INTEL)
 		intel_cpu_detect_tlb(c);
 
 	printk(KERN_INFO "Last level iTLB entries: 4KB %d, 2MB %d, 4MB %d\n" \
-		"Last level dTLB entries: 4KB %d, 2MB %d, 4MB %d\n",
+		"Last level dTLB entries: 4KB %d, 2MB %d, 4MB %d\n"	     \
+		"tlb_flushall_factor is 1/%d\n",
 		tlb_lli_4k[ENTRIES], tlb_lli_2m[ENTRIES],
 		tlb_lli_4m[ENTRIES], tlb_lld_4k[ENTRIES],
-		tlb_lld_2m[ENTRIES], tlb_lld_4m[ENTRIES]);
+		tlb_lld_2m[ENTRIES], tlb_lld_4m[ENTRIES],
+		tlb_flushall_factor);
 }
 
 void __cpuinit detect_ht(struct cpuinfo_x86 *c)
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 86e6131..42480c6 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -610,6 +610,35 @@ void intel_tlb_lookup(const unsigned char desc)
 	}
 }
 
+void intel_tlb_flushall_factor_set(struct cpuinfo_x86 *c)
+{
+	switch (c->x86_model) {
+	case 15: /* original 65 nm celeron/pentium/core2/xeon, "Merom"/"Conroe" */
+		tlb_flushall_factor = 0;
+		break;
+	case 26: /* 45 nm nehalem, "Bloomfield" */
+	case 30: /* 45 nm nehalem, "Lynnfield" */
+	case 37: /* 32 nm nehalem, "Clarkdale" */
+	case 44: /* 32 nm nehalem, "Gulftown" */
+	case 46: /* 45 nm nehalem-ex, "Beckton" */
+		tlb_flushall_factor = 64;
+		break;
+	case 42: /* SandyBridge */
+	case 45: /* SandyBridge, "Romely-EP" */
+		tlb_flushall_factor = 32;
+		break;
+	case 28: /* Atom */
+	case 47: /* 32 nm Xeon E7 */
+	case 14: /* 65 nm core solo/duo, "Yonah" */
+	case 22: /* single-core 65 nm celeron/core2solo "Merom-L"/"Conroe-L" */
+	case 23: /* current 45 nm celeron/core2/xeon "Penryn"/"Wolfdale" */
+	case 29: /* six-core 45 nm xeon "Dunnington" */
+
+	default:
+		tlb_flushall_factor = 0;
+	}
+}
+
 void intel_cpu_detect_tlb(struct cpuinfo_x86 *c)
 {
 	int i, j, n;
@@ -630,6 +659,7 @@ void intel_cpu_detect_tlb(struct cpuinfo_x86 *c)
 		for (j = 1 ; j < 16 ; j++)
 			intel_tlb_lookup(desc[j]);
 	}
+	intel_tlb_flushall_factor_set(c);
 }
 
 static const struct cpu_dev __cpuinitconst intel_cpu_dev = {
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 4f709e6..91896dc 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -314,8 +314,6 @@ void flush_tlb_mm(struct mm_struct *mm)
 	preempt_enable();
 }
 
-#define FLUSHALL_BAR	16
-
 static inline int has_large_page(struct mm_struct *mm,
 				 unsigned long start, unsigned long end)
 {
@@ -343,7 +341,8 @@ void flush_tlb_range(struct vm_area_struct *vma,
 {
 	struct mm_struct *mm;
 
-	if (!cpu_has_invlpg || vma->vm_flags & VM_HUGETLB) {
+	if (!cpu_has_invlpg || vma->vm_flags & VM_HUGETLB
+				|| !tlb_flushall_factor) {
 flush_all:
 		flush_tlb_mm(vma->vm_mm);
 		return;
@@ -364,7 +363,8 @@ flush_all:
 			act_entries = tlb_entries > mm->total_vm ?
 					mm->total_vm : tlb_entries;
 
-			if ((end - start)/PAGE_SIZE > act_entries/FLUSHALL_BAR)
+			if ((end - start)/PAGE_SIZE >
+					act_entries/tlb_flushall_factor)
 				local_flush_tlb();
 			else {
 				if (has_large_page(mm, start, end)) {
-- 
1.7.0.1

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