x86/tlb: fall back to flush all when meet a THP large page (d8dfe60d) · Commits · 戴 / test

We don't need to flush large pages by PAGE_SIZE step, that just waste time. and actually, large page don't need 'invlpg' optimizing according to our micro benchmark. So, just flush whole TLB is enough for them. The following result is tested on a 2CPU * 4cores * 2HT NHM EP machine, with THP 'always' setting. Multi-thread testing, '-t' paramter is thread number: without this patch with this patch ./mprotect -t 1 14ns 13ns ./mprotect -t 2 13ns 13ns ./mprotect -t 4 12ns 11ns ./mprotect -t 8 14ns 10ns ./mprotect -t 16 28ns 28ns ./mprotect -t 32 54ns 52ns ./mprotect -t 128 200ns 200ns Signed-off-by:

Alex Shi <alex.shi@intel.com> Link: http://lkml.kernel.org/r/1340845344-27557-4-git-send-email-alex.shi@intel.com Signed-off-by:

H. Peter Anvin <hpa@zytor.com>

arch/x86/mm/tlb.c

+34 −0

Original line number	Diff line number	Diff line
		@@ -318,12 +318,42 @@ void flush_tlb_mm(struct mm_struct *mm)

		#define FLUSHALL_BAR 16

		#ifdef CONFIG_TRANSPARENT_HUGEPAGE
		static inline unsigned long has_large_page(struct mm_struct *mm,
		unsigned long start, unsigned long end)
		{
		pgd_t *pgd;
		pud_t *pud;
		pmd_t *pmd;
		unsigned long addr = ALIGN(start, HPAGE_SIZE);
		for (; addr < end; addr += HPAGE_SIZE) {
		pgd = pgd_offset(mm, addr);
		if (likely(!pgd_none(*pgd))) {
		pud = pud_offset(pgd, addr);
		if (likely(!pud_none(*pud))) {
		pmd = pmd_offset(pud, addr);
		if (likely(!pmd_none(*pmd)))
		if (pmd_large(*pmd))
		return addr;
		}
		}
		}
		return 0;
		}
		#else
		static inline unsigned long has_large_page(struct mm_struct *mm,
		unsigned long start, unsigned long end)
		{
		return 0;
		}
		#endif
		void flush_tlb_range(struct vm_area_struct *vma,
		unsigned long start, unsigned long end)
		{
		struct mm_struct *mm;

		if (!cpu_has_invlpg \|\| vma->vm_flags & VM_HUGETLB) {
		flush_all:
		flush_tlb_mm(vma->vm_mm);
		return;
		}
		@@ -346,6 +376,10 @@ void flush_tlb_range(struct vm_area_struct *vma,
		if ((end - start)/PAGE_SIZE > act_entries/FLUSHALL_BAR)
		local_flush_tlb();
		else {
		if (has_large_page(mm, start, end)) {
		preempt_enable();
		goto flush_all;
		}
		for (addr = start; addr < end;
		addr += PAGE_SIZE)
		__flush_tlb_single(addr);

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