[PATCH] swap: cond_resched in swap_cgroup_prepare()

[PATCH] swap: cond_resched in swap_cgroup_prepare()

[Yu Zhao]

Saw need_resched() warnings when swapping on large swapfile (TBs)
because page allocation in swap_cgroup_prepare() took too long.

We already cond_resched when freeing page in swap_cgroup_swapoff().
Do the same for the page allocation.

Signed-off-by: Yu Zhao <yuzhao@google.com>
---
 mm/swap_cgroup.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/swap_cgroup.c b/mm/swap_cgroup.c
index ac6318a064d3..3405b4ee1757 100644
--- a/mm/swap_cgroup.c
+++ b/mm/swap_cgroup.c
@@ -48,6 +48,9 @@ static int swap_cgroup_prepare(int type)
 		if (!page)
 			goto not_enough_page;
 		ctrl->map[idx] = page;
+
+		if (!(idx % SWAP_CLUSTER_MAX))
+			cond_resched();
 	}
 	return 0;
 not_enough_page:
-- 
2.13.0.219.gdb65acc882-goog

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [PATCH] swap: cond_resched in swap_cgroup_prepare()

[Michal Hocko]

On Thu 01-06-17 12:56:35, Yu Zhao wrote:
> Saw need_resched() warnings when swapping on large swapfile (TBs)
> because page allocation in swap_cgroup_prepare() took too long.

Hmm, but the page allocator makes sure to cond_resched for sleeping
allocations. I guess what you mean is something different. It is not the
allocation which took too look but there are too many of them and none
of them sleeps because there is enough memory and the allocator doesn't
sleep in that case. Right?

> We already cond_resched when freeing page in swap_cgroup_swapoff().
> Do the same for the page allocation.
> 
> Signed-off-by: Yu Zhao <yuzhao-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>

The patch itself makes sense to me, the changelog could see some
clarification but other than that
Acked-by: Michal Hocko <mhocko-IBi9RG/b67k@public.gmane.org>

> ---
>  mm/swap_cgroup.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/mm/swap_cgroup.c b/mm/swap_cgroup.c
> index ac6318a064d3..3405b4ee1757 100644
> --- a/mm/swap_cgroup.c
> +++ b/mm/swap_cgroup.c
> @@ -48,6 +48,9 @@ static int swap_cgroup_prepare(int type)
>  		if (!page)
>  			goto not_enough_page;
>  		ctrl->map[idx] = page;
> +
> +		if (!(idx % SWAP_CLUSTER_MAX))
> +			cond_resched();
>  	}
>  	return 0;
>  not_enough_page:
> -- 
> 2.13.0.219.gdb65acc882-goog

-- 
Michal Hocko
SUSE Labs

Re: [PATCH] swap: cond_resched in swap_cgroup_prepare()

[Yu Zhao]

On Fri, Jun 02, 2017 at 10:18:57AM +0200, Michal Hocko wrote:
> On Thu 01-06-17 12:56:35, Yu Zhao wrote:
> > Saw need_resched() warnings when swapping on large swapfile (TBs)
> > because page allocation in swap_cgroup_prepare() took too long.
> 
> Hmm, but the page allocator makes sure to cond_resched for sleeping
> allocations. I guess what you mean is something different. It is not the
> allocation which took too look but there are too many of them and none
> of them sleeps because there is enough memory and the allocator doesn't
> sleep in that case. Right?
> 
> > We already cond_resched when freeing page in swap_cgroup_swapoff().
> > Do the same for the page allocation.
> > 
> > Signed-off-by: Yu Zhao <yuzhao@google.com>
> 
> The patch itself makes sense to me, the changelog could see some
> clarification but other than that
> Acked-by: Michal Hocko <mhocko@suse.com>

Thanks, I'll clarify the problem in the commit message and resend the
patch.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [PATCH] swap: cond_resched in swap_cgroup_prepare()

[Vladimir Davydov]

On Thu, Jun 01, 2017 at 12:56:35PM -0700, Yu Zhao wrote:
> Saw need_resched() warnings when swapping on large swapfile (TBs)
> because page allocation in swap_cgroup_prepare() took too long.
> 
> We already cond_resched when freeing page in swap_cgroup_swapoff().
> Do the same for the page allocation.
> 
> Signed-off-by: Yu Zhao <yuzhao-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>

Acked-by: Vladimir Davydov <vdavydov.dev-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

> ---
>  mm/swap_cgroup.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/mm/swap_cgroup.c b/mm/swap_cgroup.c
> index ac6318a064d3..3405b4ee1757 100644
> --- a/mm/swap_cgroup.c
> +++ b/mm/swap_cgroup.c
> @@ -48,6 +48,9 @@ static int swap_cgroup_prepare(int type)
>  		if (!page)
>  			goto not_enough_page;
>  		ctrl->map[idx] = page;
> +
> +		if (!(idx % SWAP_CLUSTER_MAX))
> +			cond_resched();
>  	}
>  	return 0;
>  not_enough_page:

We should probably do the same on the error path.

[PATCH v2] swap: cond_resched in swap_cgroup_prepare()

[Yu Zhao]

Saw need_resched() warnings when swapping on large swapfile (TBs)
because continuously allocating many pages in swap_cgroup_prepare()
took too long.

We already cond_resched when freeing page in swap_cgroup_swapoff().
Do the same for the page allocation.

Signed-off-by: Yu Zhao <yuzhao-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Acked-by: Michal Hocko <mhocko-IBi9RG/b67k@public.gmane.org>
Acked-by: Vladimir Davydov <vdavydov.dev-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
Changelog since v1:
* clarify the problem in the commit message

 mm/swap_cgroup.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/swap_cgroup.c b/mm/swap_cgroup.c
index ac6318a064d3..3405b4ee1757 100644
--- a/mm/swap_cgroup.c
+++ b/mm/swap_cgroup.c
@@ -48,6 +48,9 @@ static int swap_cgroup_prepare(int type)
 		if (!page)
 			goto not_enough_page;
 		ctrl->map[idx] = page;
+
+		if (!(idx % SWAP_CLUSTER_MAX))
+			cond_resched();
 	}
 	return 0;
 not_enough_page:
-- 
2.13.0.506.g27d5fe0cd-goog

Re: [PATCH v2] swap: cond_resched in swap_cgroup_prepare()

[Michal Hocko]

[CC Andrew]

On Sun 04-06-17 13:01:09, Yu Zhao wrote:
> Saw need_resched() warnings when swapping on large swapfile (TBs)
> because continuously allocating many pages in swap_cgroup_prepare()
> took too long.
> 
> We already cond_resched when freeing page in swap_cgroup_swapoff().
> Do the same for the page allocation.
> 
> Signed-off-by: Yu Zhao <yuzhao@google.com>
> Acked-by: Michal Hocko <mhocko@suse.com>
> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
> ---
> Changelog since v1:
> * clarify the problem in the commit message
> 
>  mm/swap_cgroup.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/mm/swap_cgroup.c b/mm/swap_cgroup.c
> index ac6318a064d3..3405b4ee1757 100644
> --- a/mm/swap_cgroup.c
> +++ b/mm/swap_cgroup.c
> @@ -48,6 +48,9 @@ static int swap_cgroup_prepare(int type)
>  		if (!page)
>  			goto not_enough_page;
>  		ctrl->map[idx] = page;
> +
> +		if (!(idx % SWAP_CLUSTER_MAX))
> +			cond_resched();
>  	}
>  	return 0;
>  not_enough_page:
> -- 
> 2.13.0.506.g27d5fe0cd-goog

-- 
Michal Hocko
SUSE Labs

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>