On Tue, Feb 10, 2009 at 18:45, Benjamin Schwartz
<bmschwar@fas.harvard.edu> wrote:
Dear Python developers,
Introduction:
I am writing from the perspective of Sugar Labs [1], which produces Sugar, a
free software project written almost entirely in Python. Sugar is designed
to run on small, resource-constrained computers. So far those computers
have been mostly x86, but it seems likely to me that we will soon want to
run on ARM as well, with the new wave of small ARM laptops [2]. These
laptops are likely to run on some variant of the ARM Cortex-A8 CPU core.
The Cortex-A8 chips all contain a set of commands known as ThumbEE or
Jazelle RCT (Runtime Compilation Target) [3]. According to ARM [4]:
"""Jazelle RCT can be used to significantly reduce the code bloat associated
with AOT and JIT compilation, making AOT technology viable on mass-market
devices. It can also be used to support execution environments beyond Java,
such as Microsoft .NET Compact Framework, Python and others."""
"""Jazelle RCT provides an excellent target for any run-time compilation
technology, including JIT and AOT for .NET MSIL, Python and Perl as well as
Java. ARM is working with leading software providers to enable solutions
ready for market with Jazelle RCT."""
The Jazelle RCT system consists of 12 assembly instructions, documented at
[5] and [6].
Question:
ARM is specifically claiming that these instructions can be used to
accelerate Python interpretation.
Wow, really? One of the links below mention that?
Is there any interpreter code, in CPython
or elsewhere, that uses ThumbEE mode?
Nope.
Is there anyone working on this?
Not that has contacted us.
What would the process be to incorporate the use of ThumbEE instructions
into CPython?
Well, this all depends on how you try to integrate the instructions. If you hide it behind the macro or in a clean way that does not penalize skipping the instructions then you write a patch. But if this can't be done it would be better to maintain an external set of patches against trunk for this. This might be pushed anyway as we have slowly been shying away from platform/CPU-specific code being in the trunk, especially when it does not come from someone who has been a Python core developer for several years.
-Brett
The whitepaper mentions the Parrot interpreter specifically, but I cannot
find any indication that anyone is actually working on Jazelle RCT support
in Parrot.
Thank you,
Ben Schwartz
[1] http://sugarlabs.org/go/Main_Page
[2]
http://www.engadget.com/2009/01/09/pegatron-and-freescale-team-for-low-power-ultra-cheap-netbooks/
[3]
http://en.wikipedia.org/wiki/ARM_architecture#Thumb_Execution_Environment_.28ThumbEE.29
[4] http://www.arm.com/products/multimedia/java/jazelle_architecture.html
[5] http://infocenter.arm.com/help/topic/com.arm.doc.dui0379a/CIHBCDGA.html
[6] http://www.arm.com/pdfs/JazelleRCTWhitePaper_final1-0_.pdf
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