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

From: Michal Nazarewicz
Date: Tue Jun 14 2011 - 12:58:51 EST


On Tue, 14 Jun 2011 15:49:29 +0200, Arnd Bergmann <arnd@xxxxxxxx> 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.

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