Le 25/02/2012 23:55, Walter Bright a écrit :
On 2/25/2012 2:08 PM, Paulo Pinto wrote:
Most standard compiler malloc()/free() implementations are actually
slower than
most advanced GC algorithms.
Most straight up GC vs malloc/free benchmarks miss something crucial. A
GC allows one to do substantially *fewer* allocations. It's a lot faster
to not allocate than to allocate.
Consider C strings. You need to keep track of ownership of it. That
often means creating extra copies, rather than sharing a single copy.
Enter C++'s shared_ptr. But that works by, for each object, allocating a
*second* chunk of memory to hold the reference count. Right off the bat,
you've got twice as many allocations & frees with shared_ptr than a GC
would have.
True, but the problem of video game isn't how much computation you do to
allocate, but to deliver a frame every few miliseconds. In most cases,
it worth spending more in allocating but with a predictable result than
let the GC does its job.
I wonder how true this will become with multicore and possibility of a
100% concurrent GC.
