Date:	Sat, 19 May 2012 10:07:07 +0800
From:	Alex Shi <alex.shi@...el.com>
To:	Alex Shi <alex.shi@...el.com>
CC:	tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
	seto.hidetoshi@...fujitsu.com, borislav.petkov@....com,
	tony.luck@...el.com, luto@....edu, jbeulich@...e.com,
	rostedt@...dmis.org, ak@...ux.intel.com, akpm@...ux-foundation.org,
	eric.dumazet@...il.com, akinobu.mita@...il.com,
	linux-kernel@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH] x86/tlb: replace INVALIDATE_TLB_VECTOR by CALL_FUNCTION_VECTOR

On 05/18/2012 11:12 PM, Alex Shi wrote:

> There are only 32 INVALIDATE_TLB_VECTOR now in kernel.
> but modern x86 sever has more cpu number. That causes lock
> contention in TLB flushing.
> 
> Now, useing generic smp call function to replace it.
> In the NHM EX machine 4P * 8cores * HT = 64 CPUs, hackbench pthread
> has 3% performance increase.
> And no clear performance changes on NHM EP(16CPUs), WSM EP(23CPU)
> and SNB EP(32CPU) machines.
> 
> This patch is base on my tlb flush range support patchset.
> 
> Signed-off-by: Alex Shi <alex.shi@...el.com>



refresh this patch will more clean up, and cc to PeterZ.
Actually, I tried to keep flush_tlb_info into dedicated cache line, but did find clear help.

Comments are appreciated!

---

>From 5be7aa1b69143bf5e8f3feeac862fa9559c2cf02 Mon Sep 17 00:00:00 2001
From: Alex Shi <alex.shi@...el.com>
Date: Sat, 19 May 2012 04:35:15 +0800
Subject: [PATCH 8/8] x86/tlb: replace INVALIDATE_TLB_VECTOR by
 CALL_FUNCTION_VECTOR

There are only 32 INVALIDATE_TLB_VECTOR now in kernel.
but modern x86 sever has more cpu number. That causes lock
contention in TLB flushing.

Now, useing generic smp call function to replace it.
In the NHM EX machine 4P * 8cores * HT = 64 CPUs, hackbench pthread
has 3% performance increase.
And no clear performance changes on NHM EP(16CPUs), WSM EP(23CPU)
and SNB EP(32CPU) machines.

This patch is base on my tlb flush range support patchset.

Signed-off-by: Alex Shi <alex.shi@...el.com>
---
 arch/x86/include/asm/entry_arch.h  |    9 --
 arch/x86/include/asm/hw_irq.h      |   39 ------
 arch/x86/include/asm/irq_vectors.h |   14 +--
 arch/x86/kernel/entry_64.S         |   18 ---
 arch/x86/kernel/irqinit.c          |   73 -----------
 arch/x86/mm/tlb.c                  |  244 +++++-------------------------------
 6 files changed, 33 insertions(+), 364 deletions(-)

diff --git a/arch/x86/include/asm/entry_arch.h b/arch/x86/include/asm/entry_arch.h
index 0baa628..40afa00 100644
--- a/arch/x86/include/asm/entry_arch.h
+++ b/arch/x86/include/asm/entry_arch.h
@@ -15,15 +15,6 @@ BUILD_INTERRUPT(call_function_interrupt,CALL_FUNCTION_VECTOR)
 BUILD_INTERRUPT(call_function_single_interrupt,CALL_FUNCTION_SINGLE_VECTOR)
 BUILD_INTERRUPT(irq_move_cleanup_interrupt,IRQ_MOVE_CLEANUP_VECTOR)
 BUILD_INTERRUPT(reboot_interrupt,REBOOT_VECTOR)
-
-.irp idx,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15, \
-	16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31
-.if NUM_INVALIDATE_TLB_VECTORS > \idx
-BUILD_INTERRUPT3(invalidate_interrupt\idx,
-		 (INVALIDATE_TLB_VECTOR_START)+\idx,
-		 smp_invalidate_interrupt)
-.endif
-.endr
 #endif
 
 BUILD_INTERRUPT(x86_platform_ipi, X86_PLATFORM_IPI_VECTOR)
diff --git a/arch/x86/include/asm/hw_irq.h b/arch/x86/include/asm/hw_irq.h
index eb92a6e..978618a 100644
--- a/arch/x86/include/asm/hw_irq.h
+++ b/arch/x86/include/asm/hw_irq.h
@@ -35,40 +35,6 @@ extern void spurious_interrupt(void);
 extern void thermal_interrupt(void);
 extern void reschedule_interrupt(void);
 
-extern void invalidate_interrupt(void);
-extern void invalidate_interrupt0(void);
-extern void invalidate_interrupt1(void);
-extern void invalidate_interrupt2(void);
-extern void invalidate_interrupt3(void);
-extern void invalidate_interrupt4(void);
-extern void invalidate_interrupt5(void);
-extern void invalidate_interrupt6(void);
-extern void invalidate_interrupt7(void);
-extern void invalidate_interrupt8(void);
-extern void invalidate_interrupt9(void);
-extern void invalidate_interrupt10(void);
-extern void invalidate_interrupt11(void);
-extern void invalidate_interrupt12(void);
-extern void invalidate_interrupt13(void);
-extern void invalidate_interrupt14(void);
-extern void invalidate_interrupt15(void);
-extern void invalidate_interrupt16(void);
-extern void invalidate_interrupt17(void);
-extern void invalidate_interrupt18(void);
-extern void invalidate_interrupt19(void);
-extern void invalidate_interrupt20(void);
-extern void invalidate_interrupt21(void);
-extern void invalidate_interrupt22(void);
-extern void invalidate_interrupt23(void);
-extern void invalidate_interrupt24(void);
-extern void invalidate_interrupt25(void);
-extern void invalidate_interrupt26(void);
-extern void invalidate_interrupt27(void);
-extern void invalidate_interrupt28(void);
-extern void invalidate_interrupt29(void);
-extern void invalidate_interrupt30(void);
-extern void invalidate_interrupt31(void);
-
 extern void irq_move_cleanup_interrupt(void);
 extern void reboot_interrupt(void);
 extern void threshold_interrupt(void);
@@ -154,11 +120,6 @@ extern asmlinkage void smp_irq_move_cleanup_interrupt(void);
 extern void smp_reschedule_interrupt(struct pt_regs *);
 extern void smp_call_function_interrupt(struct pt_regs *);
 extern void smp_call_function_single_interrupt(struct pt_regs *);
-#ifdef CONFIG_X86_32
-extern void smp_invalidate_interrupt(struct pt_regs *);
-#else
-extern asmlinkage void smp_invalidate_interrupt(struct pt_regs *);
-#endif
 #endif
 
 extern void (*__initconst interrupt[NR_VECTORS-FIRST_EXTERNAL_VECTOR])(void);
diff --git a/arch/x86/include/asm/irq_vectors.h b/arch/x86/include/asm/irq_vectors.h
index 4b44487..96b5d48 100644
--- a/arch/x86/include/asm/irq_vectors.h
+++ b/arch/x86/include/asm/irq_vectors.h
@@ -17,8 +17,7 @@
  *  Vectors   0 ...  31 : system traps and exceptions - hardcoded events
  *  Vectors  32 ... 127 : device interrupts
  *  Vector  128         : legacy int80 syscall interface
- *  Vectors 129 ... INVALIDATE_TLB_VECTOR_START-1 except 204 : device interrupts
- *  Vectors INVALIDATE_TLB_VECTOR_START ... 255 : special interrupts
+ *  Vectors 129 ... 206 except 204 : device interrupts
  *
  * 64-bit x86 has per CPU IDT tables, 32-bit has one shared IDT table.
  *
@@ -119,17 +118,6 @@
  */
 #define LOCAL_TIMER_VECTOR		0xef
 
-/* up to 32 vectors used for spreading out TLB flushes: */
-#if NR_CPUS <= 32
-# define NUM_INVALIDATE_TLB_VECTORS	(NR_CPUS)
-#else
-# define NUM_INVALIDATE_TLB_VECTORS	(32)
-#endif
-
-#define INVALIDATE_TLB_VECTOR_END	(0xee)
-#define INVALIDATE_TLB_VECTOR_START	\
-	(INVALIDATE_TLB_VECTOR_END-NUM_INVALIDATE_TLB_VECTORS+1)
-
 #define NR_VECTORS			 256
 
 #define FPU_IRQ				  13
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index cdc79b5..0fa34c9 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -1015,24 +1015,6 @@ apicinterrupt LOCAL_TIMER_VECTOR \
 apicinterrupt X86_PLATFORM_IPI_VECTOR \
 	x86_platform_ipi smp_x86_platform_ipi
 
-#ifdef CONFIG_SMP
-	ALIGN
-	INTR_FRAME
-.irp idx,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15, \
-	16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31
-.if NUM_INVALIDATE_TLB_VECTORS > \idx
-ENTRY(invalidate_interrupt\idx)
-	pushq_cfi $~(INVALIDATE_TLB_VECTOR_START+\idx)
-	jmp .Lcommon_invalidate_interrupt0
-	CFI_ADJUST_CFA_OFFSET -8
-END(invalidate_interrupt\idx)
-.endif
-.endr
-	CFI_ENDPROC
-apicinterrupt INVALIDATE_TLB_VECTOR_START, \
-	invalidate_interrupt0, smp_invalidate_interrupt
-#endif
-
 apicinterrupt THRESHOLD_APIC_VECTOR \
 	threshold_interrupt smp_threshold_interrupt
 apicinterrupt THERMAL_APIC_VECTOR \
diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c
index 252981a..6e03b0d 100644
--- a/arch/x86/kernel/irqinit.c
+++ b/arch/x86/kernel/irqinit.c
@@ -171,79 +171,6 @@ static void __init smp_intr_init(void)
 	 */
 	alloc_intr_gate(RESCHEDULE_VECTOR, reschedule_interrupt);
 
-	/* IPIs for invalidation */
-#define ALLOC_INVTLB_VEC(NR) \
-	alloc_intr_gate(INVALIDATE_TLB_VECTOR_START+NR, \
-		invalidate_interrupt##NR)
-
-	switch (NUM_INVALIDATE_TLB_VECTORS) {
-	default:
-		ALLOC_INVTLB_VEC(31);
-	case 31:
-		ALLOC_INVTLB_VEC(30);
-	case 30:
-		ALLOC_INVTLB_VEC(29);
-	case 29:
-		ALLOC_INVTLB_VEC(28);
-	case 28:
-		ALLOC_INVTLB_VEC(27);
-	case 27:
-		ALLOC_INVTLB_VEC(26);
-	case 26:
-		ALLOC_INVTLB_VEC(25);
-	case 25:
-		ALLOC_INVTLB_VEC(24);
-	case 24:
-		ALLOC_INVTLB_VEC(23);
-	case 23:
-		ALLOC_INVTLB_VEC(22);
-	case 22:
-		ALLOC_INVTLB_VEC(21);
-	case 21:
-		ALLOC_INVTLB_VEC(20);
-	case 20:
-		ALLOC_INVTLB_VEC(19);
-	case 19:
-		ALLOC_INVTLB_VEC(18);
-	case 18:
-		ALLOC_INVTLB_VEC(17);
-	case 17:
-		ALLOC_INVTLB_VEC(16);
-	case 16:
-		ALLOC_INVTLB_VEC(15);
-	case 15:
-		ALLOC_INVTLB_VEC(14);
-	case 14:
-		ALLOC_INVTLB_VEC(13);
-	case 13:
-		ALLOC_INVTLB_VEC(12);
-	case 12:
-		ALLOC_INVTLB_VEC(11);
-	case 11:
-		ALLOC_INVTLB_VEC(10);
-	case 10:
-		ALLOC_INVTLB_VEC(9);
-	case 9:
-		ALLOC_INVTLB_VEC(8);
-	case 8:
-		ALLOC_INVTLB_VEC(7);
-	case 7:
-		ALLOC_INVTLB_VEC(6);
-	case 6:
-		ALLOC_INVTLB_VEC(5);
-	case 5:
-		ALLOC_INVTLB_VEC(4);
-	case 4:
-		ALLOC_INVTLB_VEC(3);
-	case 3:
-		ALLOC_INVTLB_VEC(2);
-	case 2:
-		ALLOC_INVTLB_VEC(1);
-	case 1:
-		ALLOC_INVTLB_VEC(0);
-		break;
-	}
-
 	/* IPI for generic function call */
 	alloc_intr_gate(CALL_FUNCTION_VECTOR, call_function_interrupt);
 
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 9f35028..2b39f7a 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -28,34 +28,14 @@ DEFINE_PER_CPU_SHARED_ALIGNED(struct tlb_state, cpu_tlbstate)
  *
  *	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 array slot 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.
+ *	Implemented by smp_call_function_many, Alex Shi
  */
 
-union smp_flush_state {
-	struct {
-		struct mm_struct *flush_mm;
-		unsigned long flush_start;
-		unsigned long flush_end;
-		raw_spinlock_t tlbstate_lock;
-		DECLARE_BITMAP(flush_cpumask, NR_CPUS);
-	};
-	char pad[INTERNODE_CACHE_BYTES];
-} ____cacheline_internodealigned_in_smp;
-
-/* 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 union smp_flush_state flush_state[NUM_INVALIDATE_TLB_VECTORS];
-
-static DEFINE_PER_CPU_READ_MOSTLY(int, tlb_vector_offset);
+struct flush_tlb_info {
+	struct mm_struct *flush_mm;
+	unsigned long flush_start;
+	unsigned long flush_end;
+};
 
 /*
  * We cannot call mmdrop() because we are in interrupt context,
@@ -72,45 +52,6 @@ void leave_mm(int cpu)
 EXPORT_SYMBOL_GPL(leave_mm);
 
 /*
- *
- * The flush IPI assumes that a thread switch happens in this order:
- * [cpu0: the cpu that switches]
- * 1) switch_mm() either 1a) or 1b)
- * 1a) thread switch to a different mm
- * 1a1) cpu_clear(cpu, old_mm->cpu_vm_mask);
- *	Stop ipi delivery for the old mm. This is not synchronized with
- *	the other cpus, but smp_invalidate_interrupt ignore flush ipis
- *	for the wrong mm, and in the worst case we perform a superfluous
- *	tlb flush.
- * 1a2) set cpu mmu_state to TLBSTATE_OK
- *	Now the smp_invalidate_interrupt won't call leave_mm if cpu0
- *	was in lazy tlb mode.
- * 1a3) update cpu active_mm
- *	Now cpu0 accepts tlb flushes for the new mm.
- * 1a4) cpu_set(cpu, new_mm->cpu_vm_mask);
- *	Now the other cpus will send tlb flush ipis.
- * 1a4) change cr3.
- * 1b) thread switch without mm change
- *	cpu active_mm is correct, cpu0 already handles
- *	flush ipis.
- * 1b1) set cpu mmu_state to TLBSTATE_OK
- * 1b2) test_and_set the cpu bit in cpu_vm_mask.
- *	Atomically set the bit [other cpus will start sending flush ipis],
- *	and test the bit.
- * 1b3) if the bit was 0: leave_mm was called, flush the tlb.
- * 2) switch %%esp, ie current
- *
- * The interrupt must handle 2 special cases:
- * - cr3 is changed before %%esp, ie. it cannot use current->{active_,}mm.
- * - the cpu performs speculative tlb reads, i.e. even if the cpu only
- *   runs in kernel space, the cpu could load tlb entries for user space
- *   pages.
- *
- * The good news is that cpu mmu_state is local to each cpu, no
- * write/read ordering problems.
- */
-
-/*
  * TLB flush IPI:
  *
  * 1) Flush the tlb entries if the cpu uses the mm that's being flushed.
@@ -119,173 +60,52 @@ EXPORT_SYMBOL_GPL(leave_mm);
  * Interrupts are disabled.
  */
 
-/*
- * FIXME: use of asmlinkage is not consistent.  On x86_64 it's noop
- * but still used for documentation purpose but the usage is slightly
- * inconsistent.  On x86_32, asmlinkage is regparm(0) but interrupt
- * entry calls in with the first parameter in %eax.  Maybe define
- * intrlinkage?
- */
-#ifdef CONFIG_X86_64
-asmlinkage
-#endif
-void smp_invalidate_interrupt(struct pt_regs *regs)
+static void flush_tlb_func(void *info)
 {
-	unsigned int cpu;
-	unsigned int sender;
-	union smp_flush_state *f;
-
-	cpu = smp_processor_id();
-	/*
-	 * orig_rax contains the negated interrupt vector.
-	 * Use that to determine where the sender put the data.
-	 */
-	sender = ~regs->orig_ax - INVALIDATE_TLB_VECTOR_START;
-	f = &flush_state[sender];
-
-	if (!cpumask_test_cpu(cpu, to_cpumask(f->flush_cpumask)))
-		goto out;
-		/*
-		 * This was a BUG() but until someone can quote me the
-		 * line from the intel manual that guarantees an IPI to
-		 * multiple CPUs is retried _only_ on the erroring CPUs
-		 * its staying as a return
-		 *
-		 * BUG();
-		 */
-
-	if (f->flush_mm == percpu_read(cpu_tlbstate.active_mm)) {
-		if (percpu_read(cpu_tlbstate.state) == TLBSTATE_OK) {
-			if (f->flush_end == TLB_FLUSH_ALL
-					|| !cpu_has_invlpg)
-				local_flush_tlb();
-			else if (!f->flush_end)
-				__flush_tlb_single(f->flush_start);
-			else {
-				unsigned long addr;
-				addr = f->flush_start;
-				while (addr <= f->flush_end) {
-					__flush_tlb_single(addr);
-					addr += PAGE_SIZE;
-				}
-			}
-		} else
-			leave_mm(cpu);
-	}
-out:
-	ack_APIC_irq();
-	smp_mb__before_clear_bit();
-	cpumask_clear_cpu(cpu, to_cpumask(f->flush_cpumask));
-	smp_mb__after_clear_bit();
-	inc_irq_stat(irq_tlb_count);
-}
+	struct flush_tlb_info *f = info;
 
-static void flush_tlb_others_ipi(const struct cpumask *cpumask,
-				 struct mm_struct *mm, unsigned long start,
-				 unsigned long end)
-{
-	unsigned int sender;
-	union smp_flush_state *f;
-
-	/* Caller has disabled preemption */
-	sender = this_cpu_read(tlb_vector_offset);
-	f = &flush_state[sender];
-
-	if (nr_cpu_ids > NUM_INVALIDATE_TLB_VECTORS)
-		raw_spin_lock(&f->tlbstate_lock);
-
-	f->flush_mm = mm;
-	f->flush_start = start;
-	f->flush_end = end;
-	if (cpumask_andnot(to_cpumask(f->flush_cpumask), cpumask, cpumask_of(smp_processor_id()))) {
-		/*
-		 * We have to send the IPI only to
-		 * CPUs affected.
-		 */
-		apic->send_IPI_mask(to_cpumask(f->flush_cpumask),
-			      INVALIDATE_TLB_VECTOR_START + sender);
-
-		while (!cpumask_empty(to_cpumask(f->flush_cpumask)))
-			cpu_relax();
-	}
+	if (f->flush_mm != percpu_read(cpu_tlbstate.active_mm))
+		return;
+
+	if (percpu_read(cpu_tlbstate.state) == TLBSTATE_OK) {
+		if (f->flush_end == TLB_FLUSH_ALL || !cpu_has_invlpg)
+			local_flush_tlb();
+		else if (!f->flush_end)
+			__flush_tlb_single(f->flush_start);
+		else {
+			unsigned long addr;
+			addr = f->flush_start;
+			while (addr <= f->flush_end) {
+				__flush_tlb_single(addr);
+				addr += PAGE_SIZE;
+			}
+		}
+	} else
+		leave_mm(smp_processor_id());
 
-	f->flush_mm = NULL;
-	f->flush_start = 0;
-	f->flush_end = 0;
-	if (nr_cpu_ids > NUM_INVALIDATE_TLB_VECTORS)
-		raw_spin_unlock(&f->tlbstate_lock);
 }
 
 void native_flush_tlb_others(const struct cpumask *cpumask,
 				 struct mm_struct *mm, unsigned long start,
 				 unsigned long end)
 {
+	struct flush_tlb_info info;
+	info.flush_mm = mm;
+	info.flush_start = start;
+	info.flush_end = end;
+
 	if (is_uv_system()) {
 		unsigned int cpu;
 
 		cpu = smp_processor_id();
 		cpumask = uv_flush_tlb_others(cpumask, mm, start, end, cpu);
 		if (cpumask)
-			flush_tlb_others_ipi(cpumask, mm, start, end);
+			smp_call_function_many(cpumask, flush_tlb_func,
+								&info, 1);
 		return;
 	}
-	flush_tlb_others_ipi(cpumask, mm, start, end);
-}
-
-static void __cpuinit calculate_tlb_offset(void)
-{
-	int cpu, node, nr_node_vecs, idx = 0;
-	/*
-	 * we are changing tlb_vector_offset for each CPU in runtime, but this
-	 * will not cause inconsistency, as the write is atomic under X86. we
-	 * might see more lock contentions in a short time, but after all CPU's
-	 * tlb_vector_offset are changed, everything should go normal
-	 *
-	 * Note: if NUM_INVALIDATE_TLB_VECTORS % nr_online_nodes !=0, we might
-	 * waste some vectors.
-	 **/
-	if (nr_online_nodes > NUM_INVALIDATE_TLB_VECTORS)
-		nr_node_vecs = 1;
-	else
-		nr_node_vecs = NUM_INVALIDATE_TLB_VECTORS/nr_online_nodes;
-
-	for_each_online_node(node) {
-		int node_offset = (idx % NUM_INVALIDATE_TLB_VECTORS) *
-			nr_node_vecs;
-		int cpu_offset = 0;
-		for_each_cpu(cpu, cpumask_of_node(node)) {
-			per_cpu(tlb_vector_offset, cpu) = node_offset +
-				cpu_offset;
-			cpu_offset++;
-			cpu_offset = cpu_offset % nr_node_vecs;
-		}
-		idx++;
-	}
-}
-
-static int __cpuinit tlb_cpuhp_notify(struct notifier_block *n,
-		unsigned long action, void *hcpu)
-{
-	switch (action & 0xf) {
-	case CPU_ONLINE:
-	case CPU_DEAD:
-		calculate_tlb_offset();
-	}
-	return NOTIFY_OK;
-}
-
-static int __cpuinit init_smp_flush(void)
-{
-	int i;
-
-	for (i = 0; i < ARRAY_SIZE(flush_state); i++)
-		raw_spin_lock_init(&flush_state[i].tlbstate_lock);
-
-	calculate_tlb_offset();
-	hotcpu_notifier(tlb_cpuhp_notify, 0);
-	return 0;
+	smp_call_function_many(cpumask, flush_tlb_func, &info, 1);
 }
-core_initcall(init_smp_flush);
 
 void flush_tlb_current_task(void)
 {
-- 
1.7.5.4


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