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SubjectRe: [PATCH 1/3] x86: mm: Clean up inconsistencies when flushing TLB ranges
On 12/12/2013 07:55 PM, Mel Gorman wrote:
> NR_TLB_LOCAL_FLUSH_ALL is not always accounted for correctly and the
> comparison with total_vm is done before taking tlb_flushall_shift into
> account. Clean it up.
>
> Signed-off-by: Mel Gorman <mgorman@suse.de>

Reviewed-by: Alex Shi
> ---
> arch/x86/mm/tlb.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
> index ae699b3..09b8cb8 100644
> --- a/arch/x86/mm/tlb.c
> +++ b/arch/x86/mm/tlb.c
> @@ -189,6 +189,7 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
> {
> unsigned long addr;
> unsigned act_entries, tlb_entries = 0;
> + unsigned long nr_base_pages;
>
> preempt_disable();
> if (current->active_mm != mm)
> @@ -210,18 +211,17 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
> tlb_entries = tlb_lli_4k[ENTRIES];
> else
> tlb_entries = tlb_lld_4k[ENTRIES];
> +
> /* Assume all of TLB entries was occupied by this task */

the benchmark break this assumption?
> - act_entries = mm->total_vm > tlb_entries ? tlb_entries : mm->total_vm;
> + act_entries = tlb_entries >> tlb_flushall_shift;
> + act_entries = mm->total_vm > act_entries ? act_entries : mm->total_vm;
> + nr_base_pages = (end - start) >> PAGE_SHIFT;
>
> /* tlb_flushall_shift is on balance point, details in commit log */
> - if ((end - start) >> PAGE_SHIFT > act_entries >> tlb_flushall_shift) {
> + if (nr_base_pages > act_entries || has_large_page(mm, start, end)) {
> count_vm_event(NR_TLB_LOCAL_FLUSH_ALL);
> local_flush_tlb();
> } else {
> - if (has_large_page(mm, start, end)) {
> - local_flush_tlb();
> - goto flush_all;
> - }
> /* flush range by one by one 'invlpg' */
> for (addr = start; addr < end; addr += PAGE_SIZE) {
> count_vm_event(NR_TLB_LOCAL_FLUSH_ONE);
>


--
Thanks
Alex


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