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

[harry <harry@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx>]

On Tue, 2005-11-22 at 12:06 +0000, Keir Fraser wrote:
> 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.

I have a couple of small vmallocs which will be OK as kmallocs and the others 
I'm just vmalloc-ing a chunk and then splitting it up into a number of smaller 
resources anyway so I could kmalloc them individually instead.

>   -- Keir
> 
> 


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