[PD-dev] abstraction caching

Claude Heiland-Allen claudiusmaximus at goto10.org
Wed Oct 1 12:59:41 CEST 2008


Benchmarking an Abstraction Cache for Pd
========================================

I implemented a rudimentary abstraction caching mechanism for Miller
Puckette's pd-0.41-4, which stores the parsed text ("binbuf") associated
with the class name instead of looking for files to load every time it
is instantiated.


Benchmark Mechanism
-------------------

Run 4 times, discarding first report:
$ time pd -open layer_2.pd -send "; pd quit" &>/dev/null

layer_2.pd contains 99 layer_1.pd contains 99 layer_0.pd,
total 9901 = 9801 layer 0 + 99 layer 1 + 1 layer 0


Results: Without Cache
----------------------

real    0m0.524s
user    0m0.260s
sys     0m0.256s

real    0m0.530s
user    0m0.224s
sys     0m0.276s

real    0m0.527s
user    0m0.224s
sys     0m0.296s


Results: With Cache
-------------------

real    0m0.082s
user    0m0.068s
sys     0m0.004s

real    0m0.148s
user    0m0.120s
sys     0m0.008s

real    0m0.085s
user    0m0.052s
sys     0m0.012s


Conclusion
----------

Abstraction cache gives a speed boost of more than 500% when loading
patches containing a large number of abstractions.


Further Work
------------

The main drawback (and the easiest issue to resolve) of the current
implementation is that once an abstraction is in the cache, it stays
there forever, no matter if the file is modified within or without Pd.
This could be fixed by flushing the cache immediately after the patch
is loaded (perhaps using Pd's scheduler).

Another drawback are that abstractions in different directories with
the same file name can clobber each other - the first one loaded is the
"one true abstraction" with that name, resolving this issue will be more
difficult.


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