Re: [Xen-devel] Xmalloc worst case performance and bad corner cases

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

Yes, it's not a very good allocator!

 -- Keir

On 26/9/08 23:34, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote:

> It appears that if xmalloc (Xen heap allocator) is
> used for a long sequence of n memory requests with
> the size of each request greater than a half-page,
> but less than a page, performance will be O(n**2).
> 
> True?
> 
> And because of space for a header and alignment,
> the interval is actually from slightly less than
> a half-page to slightly less than a full-page...
> and xmalloc of a few bytes less than a full-page will
> actually end up allocating two full pages!
> 
> True?
> 
> (Yes, I realize that xmalloc'ing a "long sequence"
> from Xen heap is not a good idea because the Xen
> heap is rather small, but I currently have a veneer
> using the xmalloc/xfree routines on top of the
> domain heap, and "future versions" of 64-bit combined
> heap allocation may reuse the existing allocation
> algorithm.)
> 
> Dan
> 
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