gEDA-user: C/DataDraw beats C++/STL on EDA-like benchmarks

[Bill Cox <bill@xxxxxxxxxx>]

Hi, all.

I've recently benchmarked DataDraw (datadraw.sf.net) graph databases vs
GNU C++ graphs built using STL lists.  Large graphs (4 million nodes)
were built in the shape of a mesh.  Then, simple depth first traversals
were performed starting from a corner, a hundred times.

The C/DataDraw based implementation ran 15X faster than the C++/STL
version, while using less than half the memory.

The performance difference is due mostly to cache-optimized memory
organization, which gave the DataDraw version a 16.7X lower L2 cache
miss rate, according to cachegrind.  I estimate the DataDraw version
achieved around 30X higher useful information density in the cache.
This is due to several factors, which are roughly:

Keeping like data fields together, rather than object fields: 4X
Using a memory pool per field, rather than a global pool: 2X
Using 32-bit object references rather than 64-bit pointers: 2X
Embedding next pointers in edges rather than allocating link object: 2X

The benchmarks can be found in the expamples/graph_benchmark directory
of the source code, which can be checked out with:

    svn co https://datadraw.svn.sourceforge.net/svnroot/datadraw/trunk
datadraw

Best regards,
Bill




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