Re: Allocation sinking in git HEAD
- From: Geoff Leyland <geoff_leyland@xxxxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Thu, 5 Jul 2012 13:11:12 +1200
On 4/07/2012, at 10:49 AM, Mike Pall wrote:
> Francesco Abbate wrote:
>> I'm eager to test that with some numeric code, I will probably
>> post some results!
>
> Please do!
I updated a raytrace benchmark to use vector objects, rather than go to some
trouble to avoid them, which makes the code nicer, but imposes abstraction
costs. The "old" version is available at [1] and the "new" version at [2]. A
C implementation is also available. Best of 3 times:
C: 3.5s
luajit ray-stack.lua: 7.1s
luajit ray-object.lua: 14.6s
luajit -O-sink ray-object.lua: 43.2s
lua ray-stack.lua: 231s
lua ray-object.lua: 492s
So, not quite as fast as C, the vector abstraction still costs, but allocation
sinking makes a big difference to this cost!
For the other benchmarky code I have, allocation sinking doesn't seem to make
much difference:
- Revised simplex: C 4s, LJ 5.5s, Lua > 500s. There aren't many allocations
in this to sink.
- kdtree: LJ: 45s, Lua: 145s. I wrote this to avoid small tables and I think
there are few allocations that can be avoided. It uses closures so many traces
abort.
- binary and skew heap: LJ: 39s, Lua: 140s. Most small allocations can't be
avoided. Most trace aborts are from call unroll limits.
Cheers,
Geoff
[1]https://gist.github.com/3050335
[2]https://gist.github.com/3050338
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