ARM设备是XScale-PXA270 @ 520,128MB(可能还有一些较慢的SDRAM),运行linux,总有足够的可用内存,性能与越狱的iPhone相当.

对生产数据库(sqlite)进行基准测试给了我们很有希望的结果(ARM只是
慢20-30％),所以我试着建立ruby(1.9.2p0).

rails应用程序在ARM上运行速度非常慢(从sql获取并生成10-20倍速的模板).我已经决定运行一些基准来找到瓶颈.

再次,一些结果是可以的(与我们现在使用的旧ruby1.8.6相比,比ruby1.9.2慢6倍),有些非常慢(慢20-30倍).铁.它看起来散列方法在ARM上慢了40倍.运行Ruby Benchmark Suite显示更多瓶颈,字符串,线程,数组……

我知道ARM比Atom慢,我只是没想到会有这么大的差异,特别是在sqlite运行正常之后.

在ARM上有一些Ruby漏洞,我是否需要应用一些补丁,这是否无望并且如果我想使用ARM设备或只是设备没有足够的计算能力,应该用C重写整个应用程序？

例子

def fib(n) 
  return 1 if n < 2
  fib(n-1)+fib(n-2)
end 

Benchmark.bm do |x| 
  x.report { fib(32) }
  x.report { fib(36) }
  x.report { h = {}; (0..10**3).each {|i| h[i] = i}  } 
  x.report { h = {}; (0..10**4).each {|i| h[i] = i}  } 
  x.report { h = {}; (0..10**5).each {|i| h[i] = i}  } 
end

ruby -rbenchmark bench.rb

Atom N270,1GB

ruby 1.9.2p0 (2010-08-18) [i686-linux]
      user     system      total        real
  2.440000   0.000000   2.440000 (  2.459400)
 16.780000   0.030000  16.810000 ( 17.293015)
  0.000000   0.000000   0.000000 (  0.001180)
  0.020000   0.000000   0.020000 (  0.012180)
  0.160000   0.000000   0.160000 (  0.161803)

ruby 1.8.6 (2008-08-11 patchlevel 287) [i686-linux]
      user     system      total        real
 12.500000   0.020000  12.520000 ( 12.628106)
 84.450000   0.170000  84.620000 ( 85.879380)
  0.010000   0.000000   0.010000 (  0.002216)
  0.040000   0.000000   0.040000 (  0.032939)
  0.240000   0.010000   0.250000 (  0.255756)

XScale-PXA270 @ 520,128MB
ruby 1.9.2p0(2010-08-18)[arm-linux]

      user     system      total        real
 12.470000   0.000000  12.470000 ( 12.526507)
 85.480000   0.000000  85.480000 ( 85.939294)
  0.

0   0.000000   0.

0 (  0.060643)

  0.640000   0.000000   0.640000 (  0.642136)

  6.460000   0.130000   6.590000 (  6.605553)
建立：


 ./configure --host=arm-linux --without-X11 --disable-largefile \
--enable-socket=yes --without-Win32API --disable-ipv6 \
--disable-install-doc --prefix=/opt --with-openssl-include=/opt/include/ \
--with-openssl-lib=/opt/include/lib

ENV:

PFX=arm-iwmmxt-linux-gnueabi

export DISCIMAGE="/opt"
export CROSS_COMPILE="arm-linux-"
export HOST="arm-linux"
export TARGET="arm-linux"
export CROSS_COMPILING=1
export CC=$PFX-gcc
export CFLAGS="-O3 -I/opt/include"
export LDFLAGS="-O3 -L/opt/lib/"
#LIBS=
#CPPFLAGS=
export CXX=$PFX-g++
#CXXFLAGS=
export CPP=$PFX-cpp

export OBJCOPY="$PFX-objcopy"
export LD="$PFX-ld"
export AR="$PFX-ar" 
export RANLIB="$PFX-ranlib"
export NM="$PFX-nm"
export STRIP="$PFX-strip"
export ac_cv_func_setpgrp_void=yes
export ac_cv_func_isinf=no
export ac_cv_func_isnan=no
export ac_cv_func_finite=no


def fib(n) 
  return 1 if n < 2
  fib(n-1)+fib(n-2)
end 

Benchmark.bm do |x| 
  x.report { fib(32) }
  x.report { fib(36) }
  x.report { h = {}; (0..10**3).each {|i| h[i] = i}  } 
  x.report { h = {}; (0..10**4).each {|i| h[i] = i}  } 
  x.report { h = {}; (0..10**5).each {|i| h[i] = i}  } 
enddef fib(n) 
  return 1 if n < 2
  fib(n-1)+fib(n-2)
end 

Benchmark.bm do |x| 
  x.report { fib(32) }
  x.report { fib(36) }
  x.report { h = {}; (0..10**3).each {|i| h[i] = i}  } 
  x.report { h = {}; (0..10**4).each {|i| h[i] = i}  } 
  x.report { h = {}; (0..10**5).each {|i| h[i] = i}  } 
end