[pypy-svn] r78606 - pypy/extradoc/sprintinfo/ddorf2010

[cfbolz at codespeak.net]

Author: cfbolz
Date: Sun Oct 31 14:48:04 2010
New Revision: 78606

Added:
   pypy/extradoc/sprintinfo/ddorf2010/report.rst
Log:
draft of a sprint report


Added: pypy/extradoc/sprintinfo/ddorf2010/report.rst
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+Düsseldorf Sprint Report 2010
+==============================
+
+This years installment of the yearly PyPy Düsseldorf Sprint is drawing to a
+close. As usual, we worked in the seminar room of the `programming language
+group`_ at the University of Düsseldorf. The sprint was different from previous
+ones in that we had fewer people than usual and many actually live in
+Düsseldorf all the time. 
+
+David spent the sprint working on the `arm-backend`_ branch, which is adding an
+ARM backend to the JIT. With the help of Armin he added support for bridges in
+the JIT and generally implemented missing operations, mostly for handling integers.
+
+.. _`arm-backend`: http://codespeak.net/svn/pypy/branch/arm-backend/
+
+Ronny and Anto worked the whole week trying to come up with a scheme for
+importing PyPy's SVN history into a mercurial repository without loosing too
+much information. This is a non-trivial task, because PyPy's history is gnarly.
+We are nearly at revision 79000 and when we started using it, Subversion was at
+version 0.1. All possible and impossible ways to mangle and mistreat a
+Subversion repository have been applied to PyPy's repo, so most of the
+importing tools just give up. Ronny and Anto came up with a new plan and new
+helper scripts every day, only to then discover another corner case that they
+hadn't thought of. Now they might actually have a final plan (but they said
+that every day, so who knows?).
+
+Carl Friedrich and Lukas started working in earnest on memory benchmarks to
+understand the memory behaviour of Python code better. They have now
+implemented a generic memory benchmark runner and a simple analysis that walks
+all objectsf and collects size information about them. They also added some
+benchmarks that were proposed in the comments of the recent `call for
+benchmarks`_. As soon as some results from that work are there, we will post
+about them.
+
+.. _`call for benchmarks`: http://morepypy.blogspot.com/2010/08/call-for-benchmarks.html
+
+There were also some minor tasks performed during the sprint. Armin implemented
+the ``_bisect`` module and the ``dict.popitem`` method in RPython. Armin and
+Carl Friedrich made the new memory-saving mapdict implementation more suitable
+to use without the JIT (blog post should come about that too, at some point).
+They also made classes with custom metaclasses a lot faster when the JIT is
+used.
+
+The last three days of the sprint were spent working on Håkan's
+`jit-unroll-loops`_ branch.  The branch is meant to move loop invariants out of
+the loop, using techniques very similar to what is described in the recent post
+on `escape analysis across loop boundaries`_ (see? it will soon stop being
+science-fiction). Some of the ideas of this approach also come from LuaJIT_
+which also uses very aggressive loop invariant code motion in its optimizers.
+Moving loop invariants outside of the loop is very useful, because many of the
+lookups that Python programs do in loops are loop invariants. An example is if
+you call a function in a loop: The global lookup can often be done only once. 
+
+This branch fundamentally changes some of the core assumptions of the JIT, so
+it is a huge amount of work to make it fit with all the other parts and to
+adapt all tests. That work is now nearly done, some failing tests remain. The
+next steps are to fix them and then do additional tests with the translated
+executable and look at the benchmarks.
+
+.. _`jit-unroll-loops`: http://codespeak.net/svn/pypy/branch/jit-unroll-loops/
+.. _`escape analysis across loop boundaries`: http://morepypy.blogspot.com/2010/09/using-escape-analysis-across-loop.html
+.. _LuaJIT: http://luajit.org/