linux-kernel - Re: [PATCH] Physical Memory Management [0/1]

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Message-id: <op.utw4fdhz7p4s8u@amdc030>
Date:	Thu, 14 May 2009 13:48:39 +0200
From:	Michał Nazarewicz <m.nazarewicz@...sung.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, m.szyprowski@...sung.com,
	kyungmin.park@...sung.com, linux-mm@...ck.org
Subject: Re: [PATCH] Physical Memory Management [0/1]

> On Thu, 2009-05-14 at 11:00 +0200, Michał Nazarewicz wrote:
>>   PMM solves this problem since the buffers are allocated when they
>>   are needed.

On Thu, 14 May 2009 13:20:02 +0200, Peter Zijlstra wrote:
> Ha - only when you actually manage to allocate things. Physically
> contiguous allocations are exceedingly hard once the machine has been
> running for a while.

PMM reserves memory during boot time using alloc_bootmem_low_pages().
After this is done, it can allocate buffers from reserved pool.

The idea here is that there are n hardware accelerators, each
can operate on 1MiB blocks (to simplify assume that's the case).
However, we know that at most m < n devices will be used at the same
time so instead of reserving n MiBs of memory we reserve only m MiBs.

-- 
Best regards,                                            _     _
 .o. | Liege of Serenly Enlightened Majesty of         o' \,=./ `o
 ..o | Computer Science,  Michał "mina86" Nazarewicz      (o o)
 ooo +-<m.nazarewicz@...sung.com>-<mina86@...ber.org>-ooO--(_)--Ooo--

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