Re: Lua/LuaJIT2 performance on Android

[Josh Haberman <jhaberman@...>]

Mike Pall <mikelu-1104 <at> mike.de> writes:
> Adam Strzelecki wrote:
> > Mike, just wanted to ask whether support for VFP/NEON
> > instruction somewhere close on roadmap?
> 
> The sponsorship currently only entails an ARMv5 soft-float port.
> It may be extended later to add VFP support or new features of
> ARMv6/ARMv7. But at this time I do not have a covenant for this.

All this talk of ARM inspired me to try out LuaJIT on a new
ARM-based computer I just bought (the Efika MX Smarttop,
powered by an ARM Cortex-A8).  When I tried to compile LuaJIT,
I got:

lj_arch.h:195: error: #error "No support for Thumb instruction set (yet)"

I thought Thumb was just an extension to the ARM ISA, so I just
commented out the #error and it seems to work!  Here are my
scimark.lua numbers:

$ ./src/luajit scimark.lua 
Lua SciMark 2010-12-10 based on SciMark 2.0a. Copyright (C) 2006-2010 Mike Pall.

FFT         2.28  [1024]
SOR         6.94  [100]
MC          1.76  
SPARSE      4.90  [1000, 5000]
LU          5.57  [100]

SciMark     4.29  [small problem sizes]


$ lua scimark.lua 
Lua SciMark 2010-12-10 based on SciMark 2.0a. Copyright (C) 2006-2010 Mike Pall.

FFT         1.41  [1024]
SOR         2.95  [100]
MC          0.92  
SPARSE      1.63  [1000, 5000]
LU          1.95  [100]

SciMark     1.77  [small problem sizes]

Mike, is there a reason to error out on machines that support
Thumb?

Josh