Author: Armin Rigo <ar...@tunes.org> Branch: extradoc Changeset: r5354:192a9484ee46 Date: 2014-07-14 23:05 +0200 http://bitbucket.org/pypy/extradoc/changeset/192a9484ee46/
Log: draft of a draft diff --git a/talk/ep2014/stm/talk.rst b/talk/ep2014/stm/talk.rst new file mode 100644 --- /dev/null +++ b/talk/ep2014/stm/talk.rst @@ -0,0 +1,62 @@ +------------------------------------------------------------------------------ +Using All These Cores: Transactional Memory in PyPy +------------------------------------------------------------------------------ + + +=========================================== +Part 1 - Intro and Current Status +=========================================== + +xxx + + +=========================================== +Part 2 - Under The Hood +=========================================== + + +- pictures "GIL" and "no GIL" + +- zoom with reads and writes + +- keep boundaries, each block is a _transaction_ + +- completely the same semantics as when run with a GIL + +- write-write conflict + +- deadlock detection and resolution by abort-retry + +- read-write conflict: avoids (1) crashes, + (2) reads-from-the-past, (3) reads-from-the-future + +- reads are more common than writes: optimize read barriers + +- pypy-stm: write a thread-local flag "this object has been read", + show code for read barrier and fast-path of write barrier + +- reads are not synchronized at all between CPUs, but it's wrong + to read data written by other in-progress transactions; + so we have to write elsewhere + +- but what if we read later an object we modified? doing any kind + of check in the read barrier makes it much more costly + +- a solution would be to give each thread its own "segment" of + memory, and copy data between them only at known points + +- mmap trick: we do that, but we use mmap sharing to view the same + pages of memory at several addresses in memory + +- show clang source code and assembler for %gs + +- picture with 15/16 objects, 1/16 read markers, one page control data + +- picture with nursery -- the GC can use the same write barrier + + +=========================================== +Part 3 - Multithreading Revisited +=========================================== + +xxx _______________________________________________ pypy-commit mailing list pypy-commit@python.org https://mail.python.org/mailman/listinfo/pypy-commit
