From: Vlastimil Babka <vbabka@suse.cz>
To: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Rik van Riel <riel@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
mgorman@techsingularity.net, Laura Abbott <lauraa@codeaurora.org>,
Minchan Kim <minchan@kernel.org>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Michal Nazarewicz <mina86@mina86.com>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 3/6] mm/cma: populate ZONE_CMA
Date: Wed, 26 Oct 2016 09:27:33 +0200 [thread overview]
Message-ID: <49fde512-15dd-33dc-2120-a6ac1491a165@suse.cz> (raw)
In-Reply-To: <20161026043123.GA2901@js1304-P5Q-DELUXE>
On 10/26/2016 06:31 AM, Joonsoo Kim wrote:
> Hello,
>
> Here comes fixed one.
>
> ----------->8------------
> From 93fb05a83d74f9e2c8caebc2fa6d1a8807c9ffb6 Mon Sep 17 00:00:00 2001
> From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Date: Thu, 24 Mar 2016 22:29:10 +0900
> Subject: [PATCH] mm/cma: populate ZONE_CMA
>
> Until now, reserved pages for CMA are managed in the ordinary zones
> where page's pfn are belong to. This approach has numorous problems
> and fixing them isn't easy. (It is mentioned on previous patch.)
> To fix this situation, ZONE_CMA is introduced in previous patch, but,
> not yet populated. This patch implement population of ZONE_CMA
> by stealing reserved pages from the ordinary zones.
>
> Unlike previous implementation that kernel allocation request with
> __GFP_MOVABLE could be serviced from CMA region, allocation request only
> with GFP_HIGHUSER_MOVABLE can be serviced from CMA region in the new
> approach. This is an inevitable design decision to use the zone
> implementation because ZONE_CMA could contain highmem. Due to this
> decision, ZONE_CMA will work like as ZONE_HIGHMEM or ZONE_MOVABLE.
>
> I don't think it would be a problem because most of file cache pages
> and anonymous pages are requested with GFP_HIGHUSER_MOVABLE. It could
> be proved by the fact that there are many systems with ZONE_HIGHMEM and
> they work fine. Notable disadvantage is that we cannot use these pages
> for blockdev file cache page, because it usually has __GFP_MOVABLE but
> not __GFP_HIGHMEM and __GFP_USER. But, in this case, there is pros and
> cons. In my experience, blockdev file cache pages are one of the top
> reason that causes cma_alloc() to fail temporarily. So, we can get more
> guarantee of cma_alloc() success by discarding that case.
>
> Implementation itself is very easy to understand. Steal when cma area is
> initialized and recalculate various per zone stat/threshold.
>
> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
WARNING: multiple messages have this Message-ID (diff)
From: Vlastimil Babka <vbabka@suse.cz>
To: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Rik van Riel <riel@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
mgorman@techsingularity.net, Laura Abbott <lauraa@codeaurora.org>,
Minchan Kim <minchan@kernel.org>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Michal Nazarewicz <mina86@mina86.com>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 3/6] mm/cma: populate ZONE_CMA
Date: Wed, 26 Oct 2016 09:27:33 +0200 [thread overview]
Message-ID: <49fde512-15dd-33dc-2120-a6ac1491a165@suse.cz> (raw)
In-Reply-To: <20161026043123.GA2901@js1304-P5Q-DELUXE>
On 10/26/2016 06:31 AM, Joonsoo Kim wrote:
> Hello,
>
> Here comes fixed one.
>
> ----------->8------------
> From 93fb05a83d74f9e2c8caebc2fa6d1a8807c9ffb6 Mon Sep 17 00:00:00 2001
> From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Date: Thu, 24 Mar 2016 22:29:10 +0900
> Subject: [PATCH] mm/cma: populate ZONE_CMA
>
> Until now, reserved pages for CMA are managed in the ordinary zones
> where page's pfn are belong to. This approach has numorous problems
> and fixing them isn't easy. (It is mentioned on previous patch.)
> To fix this situation, ZONE_CMA is introduced in previous patch, but,
> not yet populated. This patch implement population of ZONE_CMA
> by stealing reserved pages from the ordinary zones.
>
> Unlike previous implementation that kernel allocation request with
> __GFP_MOVABLE could be serviced from CMA region, allocation request only
> with GFP_HIGHUSER_MOVABLE can be serviced from CMA region in the new
> approach. This is an inevitable design decision to use the zone
> implementation because ZONE_CMA could contain highmem. Due to this
> decision, ZONE_CMA will work like as ZONE_HIGHMEM or ZONE_MOVABLE.
>
> I don't think it would be a problem because most of file cache pages
> and anonymous pages are requested with GFP_HIGHUSER_MOVABLE. It could
> be proved by the fact that there are many systems with ZONE_HIGHMEM and
> they work fine. Notable disadvantage is that we cannot use these pages
> for blockdev file cache page, because it usually has __GFP_MOVABLE but
> not __GFP_HIGHMEM and __GFP_USER. But, in this case, there is pros and
> cons. In my experience, blockdev file cache pages are one of the top
> reason that causes cma_alloc() to fail temporarily. So, we can get more
> guarantee of cma_alloc() success by discarding that case.
>
> Implementation itself is very easy to understand. Steal when cma area is
> initialized and recalculate various per zone stat/threshold.
>
> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
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next prev parent reply other threads:[~2016-10-26 7:27 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-14 3:03 [PATCH v6 0/6] Introduce ZONE_CMA js1304
2016-10-14 3:03 ` js1304
2016-10-14 3:03 ` [PATCH v6 1/6] mm/page_alloc: don't reserve ZONE_HIGHMEM for ZONE_MOVABLE request js1304
2016-10-14 3:03 ` js1304
2016-10-14 3:03 ` [PATCH v6 2/6] mm/cma: introduce new zone, ZONE_CMA js1304
2016-10-14 3:03 ` js1304
2016-11-01 7:58 ` Chen Feng
2016-11-01 7:58 ` Chen Feng
2016-11-07 6:15 ` Joonsoo Kim
2016-11-07 6:15 ` Joonsoo Kim
2016-11-07 7:08 ` Chen Feng
2016-11-07 7:08 ` Chen Feng
2016-11-07 7:27 ` Joonsoo Kim
2016-11-07 7:27 ` Joonsoo Kim
2016-11-07 7:44 ` Chen Feng
2016-11-07 7:44 ` Chen Feng
2016-11-07 7:46 ` Chen Feng
2016-11-07 7:46 ` Chen Feng
2016-11-08 3:59 ` Joonsoo Kim
2016-11-08 3:59 ` Joonsoo Kim
2016-11-08 6:59 ` Chen Feng
2016-11-08 6:59 ` Chen Feng
2016-11-11 6:38 ` Joonsoo Kim
2016-11-11 6:38 ` Joonsoo Kim
2016-10-14 3:03 ` [PATCH v6 3/6] mm/cma: populate ZONE_CMA js1304
2016-10-14 3:03 ` js1304
2016-10-18 7:42 ` Vlastimil Babka
2016-10-18 7:42 ` Vlastimil Babka
2016-10-18 8:27 ` Joonsoo Kim
2016-10-18 8:27 ` Joonsoo Kim
2016-10-26 4:31 ` Joonsoo Kim
2016-10-26 4:31 ` Joonsoo Kim
2016-10-26 7:27 ` Vlastimil Babka [this message]
2016-10-26 7:27 ` Vlastimil Babka
2016-10-14 3:03 ` [PATCH v6 4/6] mm/cma: remove ALLOC_CMA js1304
2016-10-14 3:03 ` js1304
2016-10-14 3:03 ` [PATCH v6 5/6] mm/cma: remove MIGRATE_CMA js1304
2016-10-14 3:03 ` js1304
2016-10-14 3:03 ` [PATCH v6 6/6] mm/cma: remove per zone CMA stat js1304
2016-10-14 3:03 ` js1304
2016-11-07 6:25 ` [PATCH v6 0/6] Introduce ZONE_CMA Joonsoo Kim
2016-11-07 6:25 ` Joonsoo Kim
2016-11-28 7:41 ` Joonsoo Kim
2016-11-28 7:41 ` Joonsoo Kim
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