linux-kernel - Re: + mm-vmalloc-use-well-defined-find_last

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Date:	Thu, 08 Aug 2013 08:54:46 +0800
From:	Zhang Yanfei <zhangyanfei@...fujitsu.com>
To:	linux-kernel@...r.kernel.org
CC:	akpm@...ux-foundation.org, mm-commits@...r.kernel.org,
	zhangyanfei@...fujitsu.con, liwanp@...ux.vnet.ibm.com,
	hannes@...xchg.org, iamjoonsoo.kim@....com
Subject: Re: + mm-vmalloc-use-well-defined-find_last_bit-func.patch added
 to -mm tree

Hi Andrew,

于 2013/8/8 5:05, akpm@...ux-foundation.org 写道:
> Subject: + mm-vmalloc-use-well-defined-find_last_bit-func.patch added to -mm tree
> To: iamjoonsoo.kim@....com,hannes@...xchg.org,liwanp@...ux.vnet.ibm.com,zhangyanfei@...fujitsu.con
> From: akpm@...ux-foundation.org
> Date: Wed, 07 Aug 2013 14:05:29 -0700
> 
> 
> The patch titled
>      Subject: mm, vmalloc: use well-defined find_last_bit() func
> has been added to the -mm tree.  Its filename is
>      mm-vmalloc-use-well-defined-find_last_bit-func.patch
> 
> This patch should soon appear at
>     http://ozlabs.org/~akpm/mmots/broken-out/mm-vmalloc-use-well-defined-find_last_bit-func.patch
> and later at
>     http://ozlabs.org/~akpm/mmotm/broken-out/mm-vmalloc-use-well-defined-find_last_bit-func.patch
> 
> Before you just go and hit "reply", please:
>    a) Consider who else should be cc'ed
>    b) Prefer to cc a suitable mailing list as well
>    c) Ideally: find the original patch on the mailing list and do a
>       reply-to-all to that, adding suitable additional cc's
> 
> *** Remember to use Documentation/SubmitChecklist when testing your code ***
> 
> The -mm tree is included into linux-next and is updated
> there every 3-4 working days
> 
> ------------------------------------------------------
> From: Joonsoo Kim <iamjoonsoo.kim@....com>
> Subject: mm, vmalloc: use well-defined find_last_bit() func
> 
> Our intention in here is to find last_bit within the region to flush. 
> There is well-defined function, find_last_bit() for this purpose and its
> performance may be slightly better than current implementation.  So change
> it.
> 
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>
> Reviewed-by: Wanpeng Li <liwanp@...ux.vnet.ibm.com>
> Acked-by: Johannes Weiner <hannes@...xchg.org>
> Acked-by: Zhang Yanfei <zhangyanfei@...fujitsu.con>

s/zhangyanfei@...fujitsu.con/zhangyanfei@...fujitsu.com/g

> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
> ---
> 
>  mm/vmalloc.c |   15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)
> 
> diff -puN mm/vmalloc.c~mm-vmalloc-use-well-defined-find_last_bit-func mm/vmalloc.c
> --- a/mm/vmalloc.c~mm-vmalloc-use-well-defined-find_last_bit-func
> +++ a/mm/vmalloc.c
> @@ -1016,15 +1016,16 @@ void vm_unmap_aliases(void)
>  
>  		rcu_read_lock();
>  		list_for_each_entry_rcu(vb, &vbq->free, free_list) {
> -			int i;
> +			int i, j;
>  
>  			spin_lock(&vb->lock);
>  			i = find_first_bit(vb->dirty_map, VMAP_BBMAP_BITS);
> -			while (i < VMAP_BBMAP_BITS) {
> +			if (i < VMAP_BBMAP_BITS) {
>  				unsigned long s, e;
> -				int j;
> -				j = find_next_zero_bit(vb->dirty_map,
> -					VMAP_BBMAP_BITS, i);
> +
> +				j = find_last_bit(vb->dirty_map,
> +							VMAP_BBMAP_BITS);
> +				j = j + 1; /* need exclusive index */
>  
>  				s = vb->va->va_start + (i << PAGE_SHIFT);
>  				e = vb->va->va_start + (j << PAGE_SHIFT);
> @@ -1034,10 +1035,6 @@ void vm_unmap_aliases(void)
>  					start = s;
>  				if (e > end)
>  					end = e;
> -
> -				i = j;
> -				i = find_next_bit(vb->dirty_map,
> -							VMAP_BBMAP_BITS, i);
>  			}
>  			spin_unlock(&vb->lock);
>  		}
> _
> 
> Patches currently in -mm which might be from iamjoonsoo.kim@....com are
> 
> mm-hugetlb-move-up-the-code-which-check-availability-of-free-huge-page.patch
> mm-hugetlb-trivial-commenting-fix.patch
> mm-hugetlb-clean-up-alloc_huge_page.patch
> mm-hugetlb-fix-and-clean-up-node-iteration-code-to-alloc-or-free.patch
> mm-hugetlb-remove-redundant-list_empty-check-in-gather_surplus_pages.patch
> mm-hugetlb-do-not-use-a-page-in-page-cache-for-cow-optimization.patch
> mm-hugetlb-add-vm_noreserve-check-in-vma_has_reserves.patch
> mm-hugetlb-remove-decrement_hugepage_resv_vma.patch
> mm-hugetlb-decrement-reserve-count-if-vm_noreserve-alloc-page-cache.patch
> mm-hugetlb-decrement-reserve-count-if-vm_noreserve-alloc-page-cache-fix.patch
> mm-page_alloc-add-unlikely-macro-to-help-compiler-optimization.patch
> mm-move-pgtable-related-functions-to-right-place.patch
> swap-clean-up-ifdef-in-page_mapping.patch
> mm-vmalloc-remove-useless-variable-in-vmap_block.patch
> mm-vmalloc-use-well-defined-find_last_bit-func.patch
> 
> --
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> 


-- 
Thanks.
Zhang Yanfei
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