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From: Markus Trippelsdorf <markus@trippelsdorf.de>
To: Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mgorman@suse.de>, Joonsoo Kim <js1304@gmail.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
	Michal Hocko <mhocko@suse.com>
Subject: Re: [PATCH] mm: clarify COMPACTION Kconfig text
Date: Tue, 23 Aug 2016 10:38:30 +0200	[thread overview]
Message-ID: <20160823083830.GC15849@x4> (raw)
In-Reply-To: <1471939757-29789-1-git-send-email-mhocko@kernel.org>

On 2016.08.23 at 10:09 +0200, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> The current wording of the COMPACTION Kconfig help text doesn't
> emphasise that disabling COMPACTION might cripple the page allocator
> which relies on the compaction quite heavily for high order requests and
> an unexpected OOM can happen with the lack of compaction. Make sure
> we are vocal about that.

Just a few nitpicks inline below:

>  mm/Kconfig | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/Kconfig b/mm/Kconfig
> index 78a23c5c302d..0dff2f05b6d1 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -262,7 +262,14 @@ config COMPACTION
>  	select MIGRATION
>  	depends on MMU
>  	help
> -	  Allows the compaction of memory for the allocation of huge pages.
> +          Compaction is the only memory management component to form
> +          high order (larger physically contiguous) memory blocks
> +          reliably. Page allocator relies on the compaction heavily and
                       The page allo...      on compaction    
> +          the lack of the feature can lead to unexpected OOM killer
> +          invocation for high order memory requests. You shouldnm't
             invocations                                    shouldn't  
> +          disable this option unless there is really a strong reason for
                                              really is      
> +          it and then we are really interested to hear about that at
                            would be    

-- 
Markus

WARNING: multiple messages have this Message-ID (diff)
From: Markus Trippelsdorf <markus@trippelsdorf.de>
To: Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mgorman@suse.de>, Joonsoo Kim <js1304@gmail.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
	Michal Hocko <mhocko@suse.com>
Subject: Re: [PATCH] mm: clarify COMPACTION Kconfig text
Date: Tue, 23 Aug 2016 10:38:30 +0200	[thread overview]
Message-ID: <20160823083830.GC15849@x4> (raw)
In-Reply-To: <1471939757-29789-1-git-send-email-mhocko@kernel.org>

On 2016.08.23 at 10:09 +0200, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> The current wording of the COMPACTION Kconfig help text doesn't
> emphasise that disabling COMPACTION might cripple the page allocator
> which relies on the compaction quite heavily for high order requests and
> an unexpected OOM can happen with the lack of compaction. Make sure
> we are vocal about that.

Just a few nitpicks inline below:

>  mm/Kconfig | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/Kconfig b/mm/Kconfig
> index 78a23c5c302d..0dff2f05b6d1 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -262,7 +262,14 @@ config COMPACTION
>  	select MIGRATION
>  	depends on MMU
>  	help
> -	  Allows the compaction of memory for the allocation of huge pages.
> +          Compaction is the only memory management component to form
> +          high order (larger physically contiguous) memory blocks
> +          reliably. Page allocator relies on the compaction heavily and
                       The page allo...      on compaction    
> +          the lack of the feature can lead to unexpected OOM killer
> +          invocation for high order memory requests. You shouldnm't
             invocations                                    shouldn't  
> +          disable this option unless there is really a strong reason for
                                              really is      
> +          it and then we are really interested to hear about that at
                            would be    

-- 
Markus

--
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  reply	other threads:[~2016-08-23  8:38 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-23  8:09 [PATCH] mm: clarify COMPACTION Kconfig text Michal Hocko
2016-08-23  8:09 ` Michal Hocko
2016-08-23  8:38 ` Markus Trippelsdorf [this message]
2016-08-23  8:38   ` Markus Trippelsdorf
2016-08-23  9:17   ` Michal Hocko
2016-08-23  9:17     ` Michal Hocko
2016-08-25  0:54 ` David Rientjes
2016-08-25  0:54   ` David Rientjes
2016-08-25  6:54   ` Michal Hocko
2016-08-25  6:54     ` Michal Hocko
2016-08-25 22:34     ` David Rientjes
2016-08-25 22:34       ` David Rientjes
2016-08-26  6:44       ` Michal Hocko
2016-08-26  6:44         ` Michal Hocko
2016-08-29 14:10 ` Johannes Weiner
2016-08-29 14:10   ` Johannes Weiner
2016-08-29 14:50   ` Michal Hocko
2016-08-29 14:50     ` Michal Hocko

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