MMU "not in use": SYSINFO
Jonathan Gapen
In article <44db0v$8...@noc.tor.hookup.net> denn...@noc.tor.hookup.net (Robert Dennison) writes:
> Can anybody tell me why SYSINFO says that my MMU is not in use?
> (Please, no "Your MMU is not being used."
Hey, if you don't want the correct answer, what do you want? ;^)
> Is there some way to turn it on and off? I was not aware of that,
> and must assume that my system performance is suffering because of it...
The MMU is the Memory Management Unit, whose function is to sit on the
processor's address lines and manipulate address, usually translating virtual
addresses into physical memory addresses.
The AmigaOS began life on the MC68000 on the A1000, which did not have an
MMU because that would have slowed system performance by up to 20%. So even
current versions of the OS don't use the MMU, so turning it on won't affect
things.
You can use it by running a program like Enforcer to debug software, or a
virtual memory program like VMM.
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Jonathan Gapen (jag...@students.wisc.edu)
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Yambo
: You can use it by running a program like Enforcer to debug software, or a
: virtual memory program like VMM.
Or the CPU program in 2.04+ to map the ROMs (which are slower) to RAM
(which is faster.) This would give a slight performance boost for free.
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Russ 'Argel' LeBar
: Can anybody tell me why SYSINFO says that my MMU is not in use?
Your MMU is not being used. :-)
: Is there some way to turn it on and off? I was not aware of that,
: and must assume that my system performance is suffering because of it...
I think it gets activated when a program needs it (i.e. compiled to use
an MMU.
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Robert Dennison
(Please, no "Your MMU is not being used."
Is there some way to turn it on and off? I was not aware of that,
and must assume that my system performance is suffering because of it...
Thanks in advance,
Robert
Henrik Brautaset Aronsen
Hehe. Your MMU ain't in use. As soon you start programs that actually
uses the MMU (like VirtualMemoryManager(VMM) or Enforcer), sysinfo will tell
you that it's in use.. AmigaOS in it's self doesn't take advantage of the
MMU. And THAT's a shame.
Henrik
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Anders Erlandsson
> Can anybody tell me why SYSINFO says that my MMU is not in use?
>(Please, no "Your MMU is not being used."
What i know it means that there is no program using it at the moment.
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Jonathan Gapen
In article <44eaeg$7...@news.MillComm.COM> llu...@mill2.MillComm.COM (Yambo) writes:
> Jonathan Gapen (jag...@students.wisc.edu) wrote:
> : You can use it by running a program like Enforcer to debug software, or a
> : virtual memory program like VMM.
> :
> Or the CPU program in 2.04+ to map the ROMs (which are slower) to RAM
> (which is faster.) This would give a slight performance boost for free.
I've always wondered why it uses the MMU to do that, seems like a waste. I
mean, the CPU program will remap the ROM on a 68000 system. It goes away upon
reboot/crash, but the time it takes to copy ROM to RAM is neglegible, so
putting the command in the user-startup isn't a problem.
That leaves the MMU free for other things.
Scott Marlowe
: In article <44eaeg$7...@news.MillComm.COM> llu...@mill2.MillComm.COM (Yambo) writes:
: > Jonathan Gapen (jag...@students.wisc.edu) wrote:
: > : You can use it by running a program like Enforcer to debug software, or a
: > : virtual memory program like VMM.
: > :
: > Or the CPU program in 2.04+ to map the ROMs (which are slower) to RAM
: > (which is faster.) This would give a slight performance boost for free.
: I've always wondered why it uses the MMU to do that, seems like a waste. I
: mean, the CPU program will remap the ROM on a 68000 system. It goes away upon
: reboot/crash, but the time it takes to copy ROM to RAM is neglegible, so
: putting the command in the user-startup isn't a problem.
: That leaves the MMU free for other things.
No, the 68000 cannot REMAP the kickstart ram with the CPU command. As
someone with an old 68000 based machine, I know this for a fact.
On some accels there is a special command that uses resident hardware
to move the KS up to 32 bit memory, such as GVP Gforces and their
GVPCpuCtrl FASTROM command.
Jonathan Gapen
In article <44i3iq$k...@carbon.cudenver.edu> gsma...@ouray.cudenver.edu (Scott Marlowe) writes:
>
> No, the 68000 cannot REMAP the kickstart ram with the CPU command. As
> someone with an old 68000 based machine, I know this for a fact.
And I'm some one with an A500 and 2 A1000 machines that can remap the ROM
to fast memory. I've run Kickstart 3.0 from my A4000 on an A1000 just for
fun. And the A500 has no problem putting its 2.04 ROM into fast memory.
Whether it's got the same version of the 'cpu' command isn't the point
anyway. It's possible to remap the Kickstart without an MMU, and I'm
wondering why the 'cpu' command doesn't do it that way.
Patrick William Mackin
> Can anybody tell me why SYSINFO says that my MMU is not in use?
> (Please, no "Your MMU is not being used."
>
>
> and must assume that my system performance is suffering because of it...
>
>
> Thanks in advance,
>
>
> Robert
of the MMU. I don't even know when why or if the MMU is used
in Amiga programs. I *DO* know if you start a memory
monitoring program like Enforcer, sysinfo will say your mmu is
in use.
Niels Knoop
> I've always wondered why it uses the MMU to do that, seems like a waste.
It is not. It makes it possible to pretend a Kickstart from a file was
actually a ROM in its original address region, and to write-protect it.
> That leaves the MMU free for other things.
Your MMU can still function for VMM or Enforcer at the same time.
"In use" doesn't mean that it can't be assigned an additional task,
though it may somewhat restrict it.
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--
Yambo
:
: >
: > No, the 68000 cannot REMAP the kickstart ram with the CPU command. As
: > someone with an old 68000 based machine, I know this for a fact.
:
: And I'm some one with an A500 and 2 A1000 machines that can remap the ROM
: to fast memory. I've run Kickstart 3.0 from my A4000 on an A1000 just for
: fun. And the A500 has no problem putting its 2.04 ROM into fast memory.
You probably used one of the kickers that actually modifies the ROM image
(in RAM) to allow it to be relocated to a different address. This is not
the same as using the MMU to remap the ROMs to RAM, though the net result
is the same.
: Whether it's got the same version of the 'cpu' command isn't the point
: anyway. It's possible to remap the Kickstart without an MMU, and I'm
: wondering why the 'cpu' command doesn't do it that way.
:
Yes. But, the original poster wanted to know why the MMU wasn't being
used and for what could it be used.
Mariusz Szczerba
> Can anybody tell me why SYSINFO says that my MMU is not in use?
> (Please, no "Your MMU is not being used."
Try CPU-control. It must be somewhere on Aminet :-). It copies your ROM
image to RAM (you will notice significant increase of speed - accessing
ROM is much slower then RAM) making use of your MMU.
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+-----------------------------------------+
Mitch Thompson
following to say about Re: MMU "not in use": SYSINFO:
Y> Jonathan Gapen (jag...@students.wisc.edu) wrote:
Y>: You can use it by running a program like Enforcer to debug software,
Y>: or a
Y>: virtual memory program like VMM.
Y>:
Y> Or the CPU program in 2.04+ to map the ROMs (which are slower) to RAM
Y> (which is faster.) This would give a slight performance boost for free.
^^^^
Don't forget the loss of 512K(?) of RAM when doing this. There have been
times when I have had to turn the FASTROM option off...Gonna get that 4Meg RAM
upgrade this week...
Alaska, gotta love living in a state that pays you to live there ($990 this
year!)
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"The opinions and views expressed here are the opinions and views expressed
here."
Ryan O Wade
not in use, then chances are you either have a GVP accelerator or none at
all. The MMU has nothing to do with the performance of a system speedwise
The only thing it does is allows you to use Virtual Mem Managers so that
you can use part of your HD as a RAM
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Christian
wrote about "Re: MMU "not in use": SYSINFO":
JG> In article <44i3iq$k...@carbon.cudenver.edu> gsma...@ouray.cudenver.edu (Scott Marlowe) writes:
JG> >
JG> > No, the 68000 cannot REMAP the kickstart ram with the CPU command. As
JG> > someone with an old 68000 based machine, I know this for a fact.
JG>
JG> And I'm some one with an A500 and 2 A1000 machines that can remap the ROM
JG> to fast memory. I've run Kickstart 3.0 from my A4000 on an A1000 just for
JG> fun. And the A500 has no problem putting its 2.04 ROM into fast memory.
I doubt this. Either you need an MMU to put the original ROM contents
(i.e. relocated to $f80000) into fast ram or you need an additional
relocation table (which is different with each kickstart version) that
replaces all entries that refer to an absolute address with the
correct address or you already have a ROM file that is relocated to
some memory that exists on your Amiga.
JG> Whether it's got the same version of the 'cpu' command isn't the point
JG> anyway. It's possible to remap the Kickstart without an MMU, and I'm
JG> wondering why the 'cpu' command doesn't do it that way.
That's simple: C= didn't want to support pirating copies of kickstarts.
Greetings
Christian
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Frank Wille
about "Re: MMU "not in use": SYSINFO" :
Y> : to fast memory. I've run Kickstart 3.0 from my A4000 on an A1000just for
Y> : fun. And the A500 has no problem putting its 2.04 ROM into fast memory.
Y>
Y> You probably used one of the kickers that actually modifies the ROM image
Y> (in RAM) to allow it to be relocated to a different address. This is not
Y> the same as using the MMU to remap the ROMs to RAM, though the net result
Y> is the same.
The MMU has the big advantage that it can be used to write protect
the ROM image.
Greetings,
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