linux-kernel - Re: [PATCH 08/10] mm: cma: Contiguous Memory Allocator added

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Message-ID: <op.vw2r3xrj3l0zgt@mnazarewicz-glaptop>
Date:	Tue, 14 Jun 2011 18:58:35 +0200
From:	"Michal Nazarewicz" <mina86@...a86.com>
To:	"Arnd Bergmann" <arnd@...db.de>
Cc:	"Marek Szyprowski" <m.szyprowski@...sung.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-media@...r.kernel.org, linux-mm@...ck.org,
	linaro-mm-sig@...ts.linaro.org,
	"'Kyungmin Park'" <kyungmin.park@...sung.com>,
	"'Andrew Morton'" <akpm@...ux-foundation.org>,
	"'KAMEZAWA Hiroyuki'" <kamezawa.hiroyu@...fujitsu.com>,
	"'Ankita Garg'" <ankita@...ibm.com>,
	"'Daniel Walker'" <dwalker@...eaurora.org>,
	"'Mel Gorman'" <mel@....ul.ie>,
	"'Jesse Barker'" <jesse.barker@...aro.org>
Subject: Re: [PATCH 08/10] mm: cma: Contiguous Memory Allocator added

>> On Tue, 14 Jun 2011 15:49:29 +0200, Arnd Bergmann <arnd@...db.de> wrote:
>>> Please explain the exact requirements that lead you to defining  
>>> multiple contexts.

> On Tuesday 14 June 2011, Michal Nazarewicz wrote:
>> Some devices may have access only to some banks of memory.  Some devices
>> may use different banks of memory for different purposes.

On Tue, 14 Jun 2011 18:03:00 +0200, Arnd Bergmann wrote:
> For all I know, that is something that is only true for a few very  
> special Samsung devices,

Maybe.  I'm just answering your question. :)

Ah yes, I forgot that separate regions for different purposes could
decrease fragmentation.

> I would suggest going forward without having multiple regions:

Is having support for multiple regions a bad thing?  Frankly,
removing this support will change code from reading context passed
as argument to code reading context from global variable.  Nothing
is gained; functionality is lost.

> * Remove the registration of specific addresses from the initial patch
>   set (but keep the patch).
> * Add a heuristic plus command-line override to automatically come up
>   with a reasonable location+size for *one* CMA area in the system.

I'm not arguing those.

-- 
Best regards,                                         _     _
.o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
..o | Computer Science,  Michal "mina86" Nazarewicz    (o o)
ooo +-----<email/xmpp: mnazarewicz@...gle.com>-----ooO--(_)--Ooo--
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