Re: can you switch between GFP_ATOMIC and GFP_KERNEL?

[Michael Hines]

Oh, that's right.

Stupid me =)

Thanks,
/*********************************/
Michael R. Hines
Grad Student, Florida State
Dept. Computer Science
http://www.cs.fsu.edu/~mhines/
Jusqu'a ce que le futur vienne...
/*********************************/


On Fri, 31 Dec 2004, Roland Dreier wrote:

>     Michael> My question is, new sk_buffs are always allocated with
>     Michael> GFP_KERNEL and can be swapped out. Is it possible to
>     Michael> change the allocation status of already-allocated memory
>     Michael> to GFP_ATOMIC on the fly? (i.e. both the slab-cache
>     Michael> sk_buff header memory as well as the kmalloc'd data
>     Michael> area).
>
> This question is ill-posed -- kernel memory can never be swapped out,
> whether it's allocated with GFP_KERNEL or GFP_ATOMIC.  The difference
> between GFP_KERNEL and GFP_ATOMIC is whether the actual allocation can
> sleep, that is:
>
> 	foo = kmalloc(sizeof foo, GFP_ATOMIC);	/* will not sleep */
> 	foo = kmalloc(sizeof foo, GFP_KERNEL);	/* can sleep */
>
> However, whichever gfp flags are used to allocate memory, the memory
> is the same once the allocation is done.  Neither kmalloc'ed memory
> nor sk_buffs will ever be swapped.
>
>  - Roland
>

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