On 30.09.2010 23:44, Andre Oppermann wrote:
On 30.09.2010 20:04, Roman Divacky wrote:
On Thu, Sep 30, 2010 at 07:49:00PM +0200, Roman Divacky wrote:
On Thu, Sep 30, 2010 at 07:46:32PM +0200, Andre Oppermann wrote:
On 30.09.2010 19:24, Roman Divacky wrote:
are you aware of Summer of Code 2008 project by Mayur Shardul?
I remember that there was this project but I never saw any numbers
or other outcome of it. Haven't checked p4 to look at the code
though.
there's a little something:
http://wiki.freebsd.org/MayurShardul/VM_Algorithm_Improvement
and the actual patch + userspace implementation + benchmarking suite
is here:
http://code.google.com/p/google-summer-of-code-2008-freebsd/downloads/detail?name=Mayur_Shardul.tar.gz&can=2&q=
it looks like a solid work with solid results to me
I just took a look (not in-depth though) at the patch and can't follow
your conclusion. It is not ready to go into svn in its current state.
Even though it is called a radix trie it doesn't look like one. On first
impression it looks much more like an AA tree. A radix trie, which we
already have in our network routing table code, is a variable length
(mask) tree that does path compression. See net/radix.[ch] and
http://en.wikipedia.org/wiki/Radix_tree
Thinking more about this I can't see any advantage of the radix trie
becoming useful for the vmmap. The index of the vmmap is the address
range and can't be expressed in a path compressable power of 2 quantity
and is non-overlapping. The key for the trie, a pointer, has a fixed
small size and can't be optimized away. And it is not a balanced tree.
Many keys in the same region lead to long node traversals.
In short: VMmap and a radix trie have an impedance mismatch and are unfit
for each other imho.
--
Andre
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