linux-kernel - Re: [PATCH] mm/mmap.c: refine data locality of find_vma

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Date:   Thu, 8 Aug 2019 14:33:36 +0000
From:   Wei Yang <richard.weiyang@...il.com>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     Wei Yang <richardw.yang@...ux.intel.com>,
        Michal Hocko <mhocko@...nel.org>, akpm@...ux-foundation.org,
        kirill.shutemov@...ux.intel.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/mmap.c: refine data locality of find_vma_prev

On Thu, Aug 08, 2019 at 10:49:29AM +0200, Vlastimil Babka wrote:
>On 8/8/19 5:26 AM, Wei Yang wrote:
>> 
>> @@ -2270,12 +2270,9 @@ find_vma_prev(struct mm_struct *mm, unsigned long addr,
>>         if (vma) {
>>                 *pprev = vma->vm_prev;
>>         } else {
>> -               struct rb_node *rb_node = mm->mm_rb.rb_node;
>> -               *pprev = NULL;
>> -               while (rb_node) {
>> -                       *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb);
>> -                       rb_node = rb_node->rb_right;
>> -               }
>> +               struct rb_node *rb_node = rb_last(&mm->mm_rb);
>> +               *pprev = !rb_node ? NULL :
>> +                        rb_entry(rb_node, struct vm_area_struct, vm_rb);
>>         }
>>         return vma;
>> 
>> Not sure this style would help a little in understanding the code?
>
>Yeah using rb_last() would be nicer than basically repeating its
>implementation, so it's fine as a cleanup without performance implications.
>

Thanks, I would send this version with proper change log.

>>> -- 
>>> Michal Hocko
>>> SUSE Labs
>> 

-- 
Wei Yang
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