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trans closure performance evaluation.

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Sears Russell 2005-03-25 18:56:29 +00:00
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doc/paper2/LLADD.tex
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@ -2004,9 +2004,7 @@ requests by reordering invocations of wrapper functions.
\subsection {Data Representation}
We loosly base the graphs for this test on the graphs used by the oo7
benchmark~\cite{oo7}. For the test, we hardcode the outdegree of
graph nodes to 3, 6 and 9. This allows us to represent graph nodes as
For simplicity, we represent graph nodes as
fixed length records. The Array List from our linear hash table
implementation (Section~\ref{sub:Linear-Hash-Table}) provides access to an
array of such records with performance that is competive with native
@ -2125,6 +2123,30 @@ page files.
\subsection {Performance Evaluation}
We loosly base the graphs for this test on the graphs used by the oo7
benchmark~\cite{oo7}. For the test, we hardcode the outdegree of
graph nodes to 3, 6 and 9 and use a directed graph. The oo7 benchmark
constructs graphs by first connecting nodes together into a ring. It
then randomly adds edges between the nodes until the desired outdegree
is obtained. This structure ensures graph connectivity. If the nodes
are layed out in ring order on disk, it also ensures that one edge
from each node has good locality, while the others generally have poor
locality. The results for this test are presented in
Figure~\ref{oo7}, and we can see that the request reordering algorithm
helps performance. We re-ran the test without the ring edges, and (in
line with our next set of results) found that the reordering algorithm
also helped in that case.
In order to get a better feel for the effect of graph locality on the
two traversal algorithms we extend the idea of a hot set to graph
generation. Each node has a distinct hot set which includes the 10\%
of the nodes that are closest to it in ring order. The remaining
nodes are in the cold set. We use random edges instead of ring edges
for this test. Figure~\ref{hotGraph} suggests that request reordering
only helps when the graph has poor locality. This makes sense, as a
depth first search of a graph with good locality will also have good
locality. Therefore, processing a request via the queue-based multiplexer
is more expensive then making a recursive function call.
This section uses: