A thousand apologies, by keeping debugging the code I realised I made a really bad beginner's mistake, if you look at that code:
TileData(const data_key_t &key) : theKey(key), data(NULL)
{
float *data = new float [tileSize * tileSize * tileSize];
}
from the TikeData class where data is supposed to actually be a member variable of the class... So the right code should be:
class TileData
{
public:
float *data;
TileData(const data_key_t &key) : theKey(key), data(NULL)
{
data = new float [tileSize * tileSize * tileSize];
numAlloc++;
}
};
I am so sorry about that! It's a mistake I have done in the past, and I guess prototyping is great, but it sometimes lead to do such stupid mistakes. I ran the code with 1 and 4 threads and do now see the speedup. 1 thread takes about 2.3 seconds, 4 threads takes 0.92 seconds. Thanks all for your help, and sorry if I made you lose your time ;-)