Re: [PATCH] Physical Memory Management [0/1]

Michał Nazarewicz
2009-05-14T11:48:04Z

> On Thu, 2009-05-14 at 11:00 +0200, MichaA? 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.

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