Re: [Xen-devel] [PATCH][2/17] USB virt 2.6 split driver---xenidc buffer resource provider

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 22 Nov 2005, at 11:22, Muli Ben-Yehuda wrote:

> Quoth Linus[1[:
>
> "vmalloc() is NOT SOMETHING YOU SHOULD EVER USE! It's only valid for
> when you _need_ a big array, and you don't have any choice. It's slow,
> and it's a very restricted resource: it's a global resource that is
> literally restricted to a few tens of megabytes. It should be _very_
> carefully used."
He also says the correct fix is to not need a multi-page chunk in the 
first place. If you do, then you should pre-allocate. If that's 
impossible (e.g., you're a module) then you use vmalloc(). The page 
allocator does not attempt any compaction, so even if there is plenty 
of memory you may well not find a big contiguous extent.
 -- Keir


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