Re: Kernel tempory memory alloc

[Fawad Lateef <fawadlateef@gmail.com>]

On 11/19/05, James Courtier-Dutton <James@superbug.demon.co.uk> wrote:
>
> The IOCTL will be a simple request/response type, so the memory
> allocation will be for a very short time. Which is the correct memory
> api to use when allocating short term temporary memory in the kernel.

I mostly/vastly used and saw memory allocation API "kmalloc" for small
memory allocations. And for short-term and fast memory allocation use
GFP_ATOMIC flag with memory allocation functions!

> Alternatively, is there a way to handle this by simply moving a page
> from user space to kernel space and then back to user space again?
> Thus reducing the amount of memcpy.
>

I think memcpy is not a big-overhead as compare to temporary mapping a
page from user space to kernel space and then unmapping it each time
an ioctl is called, so you might try to constantly share a buffer
between user/kernel space through which you can access data directly
from both spaces (for mapping user page in kernel you can see
get_user_pages) !


--
Fawad Lateef

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