[RESOLVED] What is it with threads and performance?

[BlindSniper]

Well theoretically if you only had one processor doing them in linear or parallel would take Exactly the same time since the processor can only do X amount of calculations per second and you only have Y amount of calculations that need to be done. But if you have a dual or quad core processor theoretically it could be done faster because then you have true parallelism .

[bergerkiller]

Ah so the fact that I have a dual-core processor could explain why it is faster when using threads? Then still...why is it like 10x as fast?

EDIT

BTW: I added a picturebox which was updating from the COPY bitmap (very buggy, took a while to make it work), and it is filling the empty pixels nicely parallel.
The image looked sorta like this, dots stand for filled pixels:
..............-----------------
...........-------------------
.........--------------------
.......----------------------
etc.

[stanav]

Well theoretically if you only had one processor doing them in linear or parallel would take Exactly the same time since the processor can only do X amount of calculations per second and you only have Y amount of calculations that need to be done. But if you have a dual or quad core processor theoretically it could be done faster because then you have true parallelism .

The key term here is "theoretically". Mutithreading requires slightly more overheads than single threading and thus with a single core/thread (non-hyper threading) CPU, it'll take longer to complete the same task when multithreaded.