Performance comparison between tensor type string lookup and metatable-function selector...

callbenchmark.lua

x = torch.DoubleTensor()
y = torch.FloatTensor()

function testfunc(a,b)
return a + b
end

f = {}
f[x:type()] = {}
f[y:type()] = {}
f[x:type()].funcA = testfunc;
f[y:type()].funcA = testfunc;

m1 = getmetatable(x)
m2 = getmetatable(y)
m1.xx = {}
m2.xx = {}
m1.xx.funcA = testfunc;
m2.xx.funcA = testfunc;

function benchmark_typelookup(n,t,fn)
  for i=1,n do
    f[t:type()][fn](i,i)
  end
end

function benchmark_metatable(n,t,fn)
  for i=1,n do
    t.xx[fn](i,i)
  end
end

t = torch.tic()
benchmark_typelookup(5000000, x, 'funcA')
benchmark_typelookup(5000000, y, 'funcA')
timeA = torch.toc(t)


t = torch.tic()
benchmark_metatable(5000000, x, 'funcA')
benchmark_metatable(5000000, y, 'funcA')
timeB = torch.toc(t)

print('typelookup: ' ..timeA)
print('metatable: '..timeB)

--[[
on my machine:
typelookup: 2.3007190227509
metatable: 1.5103120803833
]]