Slow with MMuLib installed

[Zilog]

Hy Tony,
the configuration are Amiga 4000D with 68030 + MMU + FPU 68882( if present or no data cache are indifferent)
The problem are present with either winaue v3.5 and with v.3.6 beta. (before version i never tested)
Have installed workbech 3.1 or 3.9BB4, setPath , e MMulib 46.13 e MUI.
Whe Installed MMULib (too only library) the opreration to disk and the velocty of ram are more slowly:

SySpeed 2.6 Benchmark

Drive

With MMuLib Not Installed - Installed
speedDrive.jpg

Memory
With MMuLib Not Installed - Installed
speedMemoryjpg.JPG


My Configuration
@Amiga.4000_030_Os.v3.x.uae

Thanks for support.

[Toni Wilen]

MMU emulation is slow, each CPU memory access needs extra MMU translation checks. MMU emulation is mostly inactive (but will still cause some speed penalty) until MMU is enabled.

It won't increase performance like it does on real hardware. Real hardware needs help from the MMU to be able to use 68040+ caches fully (copy back mode) without major stability problems.

MMU emulation is mainly useful for debugging, development and ability to run unix-like operating systems.

68040+ MMU "fast path" probably can be optimized much more but it isn't that important because MMU is "never" needed in normal m68k AOS use.

[Zilog]

Originally Posted by Toni Wilen

.....

68040+ MMU "fast path" probably can be optimized much more but it isn't that important because MMU is "never" needed in normal m68k AOS use.

Thanks a lot for answer Tony.

[rmzalbar]

Actually, I see about a 10% performance reduction on real hardware when the MMU is in use on the 68030 (maprom, etc.) The 68030 MMU is relatively primitive and costly, unlike with the 68040+