rygorous

why doesn't radfft support AVX on PC?

So there's two separate issues here: using instructions added in AVX and using 256-bit wide vectors. The former turns out to be much easier than the latter for our use case.

Problem number 1 was that you positively need to put AVX code in a separate file with different compiler settings (/arch:AVX for VC++, -mavx for GCC/Clang) that make all SSE code emitted also use VEX encoding, and at the time radfft was written there was no way in CDep to set compiler flags for just one file, just for the overall build.

[There's the GCC "target" annotations on individual funcs, which in principle fix this, but I ran into nasty problems with this for several compiler versions, and VC++ has no equivalent, so we're not currently using that and just sticking with different compilation units.]

The other issue is to do with CPU power management.

andrejbauer

(* How do to topology in Coq if you are secretly an HOL fan.
   We will not use type classes or canonical structures because they
   count as "advanced" technology. But we will use notations.
 *)

(* We think of subsets as propositional functions.
   Thus, if [A] is a type [x : A] and [U] is a subset of [A],
   [U x] means "[x] is an element of [U]".
*)
Definition P (A : Type) := A -> Prop.

crabtw

HOST=x86_64-unknown-linux-gnu

#TARGET=mips-unknown-linux-gnu
#CROSS_TOOL=$HOME/tmp/mips-2013.05/bin
#CXX=mips-linux-gnu-g++
#CXXFLAGS="-shared -fPIC -mips32r2 -msoft-float -mabi=32"
#LLCFLAGS="-march=mips -mcpu=mips32r2 -soft-float -mattr=+mips32r2,+o32 -relocation-model=pic -disable-fp-elim -segmented-stacks"

TARGET=arm-unknown-linux-gnueabihf
CROSS_TOOL=$HOME/tmp/rpi-tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin

spion

Warning

This benchmark has been misleading for a while. It was originally made to demonstrate how JIT compilers can do all sorts of crazy stuff to your code - especially LuaJIT - and was meant to be a starting point of discussion about what exactly LuaJIT does and how.

As a result, its not indicative of what its performance may be on more realistic data. Differences can be expected because

1. the text will not consist of hard-coded constants

adulau

#!/usr/bin/perl
#
#
# This perl script is dumping the urls submitted
# by an HN user. Sometime it's better than any
# del.icio.us stream when the HN user has some
# special interests.
#
# Usage:
#