Re: [PATCH 1/2] mm: add cond_resched to generic_swapfile_activate

From	Michal Hocko <mhocko@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 1/2] mm: add cond_resched to generic_swapfile_activate
Date	2016-07-25 09:30 +0200
Message-ID	<rYIuR-1Id-1@gated-at.bofh.it> (permalink)
References	<rXQ1r-2G8-11@gated-at.bofh.it> <rXQ1s-2G8-19@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Fri 22-07-16 17:11:20, Mikulas Patocka wrote:
> The function generic_swapfile_activate can take quite long time, it iterates
> over all blocks of a file, so add cond_resched to it. I observed about 1 second
> stalls when activating a swapfile that was almost unfragmented - this patch
> fixes it.
> 
> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

Acked-by: Michal Hocko <mhocko@suse.com>

> 
> ---
>  mm/page_io.c |    2 ++
>  1 file changed, 2 insertions(+)
> 
> Index: linux-4.7-rc7/mm/page_io.c
> ===================================================================
> --- linux-4.7-rc7.orig/mm/page_io.c	2016-05-30 17:34:37.000000000 +0200
> +++ linux-4.7-rc7/mm/page_io.c	2016-07-11 17:23:33.000000000 +0200
> @@ -166,6 +166,8 @@ int generic_swapfile_activate(struct swa
>  		unsigned block_in_page;
>  		sector_t first_block;
>  
> +		cond_resched();
> +
>  		first_block = bmap(inode, probe_block);
>  		if (first_block == 0)
>  			goto bad_bmap;

-- 
Michal Hocko
SUSE Labs

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[PATCH 0/2] mm patches Mikulas Patocka <mpatocka@redhat.com> - 2016-07-22 23:20 +0200
  [PATCH 2/2] mm: optimize copy_page_to/from_iter_iovec Mikulas Patocka <mpatocka@redhat.com> - 2016-07-22 23:20 +0200
    Re: [PATCH 2/2] mm: optimize copy_page_to/from_iter_iovec Andi Kleen <andi@firstfloor.org> - 2016-07-23 23:00 +0200
  [PATCH 1/2] mm: add cond_resched to generic_swapfile_activate Mikulas Patocka <mpatocka@redhat.com> - 2016-07-22 23:20 +0200
    Re: [PATCH 1/2] mm: add cond_resched to generic_swapfile_activate Michal Hocko <mhocko@kernel.org> - 2016-07-25 09:30 +0200

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