Dolphin gamecube block cache

[MagicJack]

So I was wondering if someone could try and explain to me what the block cache in the emulator is. It seems to be the cause of a lot of lag in the game 007 nightfire for me. I can go in to more detail as to why it is the reason if needed.

[delroth]

The "block cache" you're most likely talking about is internally called the JIT cache, and it stores the result of PPC->X86 code translation + performs branch linking on compiled blocks in order to 1. avoid having to lookup jump destinations through the dispatcher when they're known; 2. avoid having to recompile code when we already have a compiled version of it.

It has to be invalidated either partially or completely at some point. Most of the time, only partially when a icbi/icbz/... instruction is used to clear the instruction cache. Very rarely, it has to be completely cleared (game disables cache, for example).

[MagicJack]

Okay thanks. Whenever I play Nightfire It starts at 60fps but slowly goes down as more enemies enter into the screen area. It seems after a while of running at 8-15fps, it automatically clears the block cache and the game speeds up instantly back up to 60fps. Is there anything I can do to make it happen more often or is this more a coded thing that isnt really controllable?

[delroth]

It's probably not related and just a consequence of something else.

[MagicJack]

Okay thanks