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Re : module allocation

To: Ralf Baechle <ralf@linux-mips.org>
Subject: Re : module allocation
From: moreau francis <francis_moreau2000@yahoo.fr>
Date: Sat, 29 Apr 2006 11:41:01 +0200 (CEST)
Cc: linux-mips@linux-mips.org
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Reply-to: moreau francis <francis_moreau2000@yahoo.fr>
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On Fri, Apr 28, 2006 at 01:04:17PM +0000, moreau francis wrote:

> Maybe a silly question...why do we use mapped memory (allocated by
> vmalloc) for inserting a module into the kernel ?
> 

Ok, to sum up things:

Pros:
  - allocation granularity is a page size  where as GFP allocations is a power
    of two...
  - better chance for the module to get loaded into fragmented memory.

Cons:
  - it consumes TLB entries, (usually one ?)
  - it needs to generate the module with "-mlong-calls" switch which generates
    larger and less efficient code.
  - there will be a refill exception overhead each time the module code will be
    executed and it's not mapped through TLB.

maybe that would make sense to do some benchmarks ?

Thanks




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