From: Shaohua Li <shaohua.li@intel.com>
Date: Tue, 15 Nov 2011 22:49:02 +0000 (-0800)
Subject: x86/mm: Avoid superflous leave_mm() in the TLB flush path
X-Git-Tag: next-20111206~21^2~2^2
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=287de5b2cb365b98190b5de8ace1c5a31768a5ae;p=karo-tx-linux.git

x86/mm: Avoid superflous leave_mm() in the TLB flush path

If just one page VA tlb is required to be flushed and current
task is in lazy TLB state, doing leave_mm() is superfluous
because it flushes the whole TLB.  This can reduce some TLB
miss.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index d6c0418c3e47..304166557366 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -153,13 +153,13 @@ void smp_invalidate_interrupt(struct pt_regs *regs)
 		 */
 
 	if (f->flush_mm == percpu_read(cpu_tlbstate.active_mm)) {
-		if (percpu_read(cpu_tlbstate.state) == TLBSTATE_OK) {
-			if (f->flush_va == TLB_FLUSH_ALL)
+		if (f->flush_va == TLB_FLUSH_ALL) {
+			if (percpu_read(cpu_tlbstate.state) == TLBSTATE_OK)
 				local_flush_tlb();
 			else
-				__flush_tlb_one(f->flush_va);
+				leave_mm(cpu);
 		} else
-			leave_mm(cpu);
+			__flush_tlb_one(f->flush_va);
 	}
 out:
 	ack_APIC_irq();
@@ -306,12 +306,8 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long va)
 
 	preempt_disable();
 
-	if (current->active_mm == mm) {
-		if (current->mm)
-			__flush_tlb_one(va);
-		else
-			leave_mm(smp_processor_id());
-	}
+	if (current->active_mm == mm)
+		__flush_tlb_one(va);
 
 	if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
 		flush_tlb_others(mm_cpumask(mm), mm, va);