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Old 17 October 2019, 21:47   #1
macce2
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Optimizing Amiga expansion memory configuration

Generally, on my A4000D there is a A3660 board, PicassoIV, Fastlane card with 40 Mb (?), eFlash4000 and optionally, BigRamPlus card installed. On the motherboard, there is a normal 16 Mb fast installed.
If I' d manage with about 60 Mb total Ram,
Would I be better off removing the BigRamPlus card completely; considering overall performance and stability ?
I use 60ns simms on my Fastlane card and have installed the Ram speed 60ns jumper. (?!)
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Old 17 October 2019, 21:53   #2
AmigaHope
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You can use a tool to adjust memory priorities so the fastest RAM gets allocated first, which means that having that extra RAM won't slow your system down and will only get used when it's needed.
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Old 18 October 2019, 04:54   #3
grelbfarlk
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Well if you run out of RAM generally you're going to have a bad day. If you don't need the RAM but the system runs happily with a little bit of power going to the BigRAMPlus, no reason to remove it.
If you run showconfig or that changemempri program it will show the memory priorities going like this:
Motherboard 40
Z3 Ram 30
Chip Memory 2

Or something like that. It's already going to use the fastest memory first. If you add an accelerator that priority is going to be something like 50, above the motherboard RAM.

But if you really have no use for the BigRAMPlus, sell it to someone that has a reason to need more memory.
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Old 18 October 2019, 14:57   #4
Photon
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Quote:
Originally Posted by AmigaHope View Post
You can use a tool to adjust memory priorities so the fastest RAM gets allocated first, which means that having that extra RAM won't slow your system down and will only get used when it's needed.
This must be a resident program and requires an extra reboot when you turn on your Amiga to allow all libs to be in the prioritized RAM AFAIK.


I would unplug all RAM boards and speedtest, then plug and play 1 at a time to find out if a board slows it down. Then still use it but deprioritize it. Because it will take a long time of power user usage to hit the top part of 60MB.
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Old 23 October 2019, 19:42   #5
AmigaHope
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Quote:
Originally Posted by Photon View Post
This must be a resident program and requires an extra reboot when you turn on your Amiga to allow all libs to be in the prioritized RAM AFAIK.


I would unplug all RAM boards and speedtest, then plug and play 1 at a time to find out if a board slows it down. Then still use it but deprioritize it. Because it will take a long time of power user usage to hit the top part of 60MB.
If you include the priority setting tool in your startup-sequence before any maprom or setpatch, you should be good. A few variables might get loaded into the slower memory but not enough to affect overall performance. I don't know how exec allocates its process table so there might be a bit of a speedup lost in heavy multitasking if it keeps insisting on using the slower memory for its table, but again not much as the vast majority of code will be in your fastest memory, and the tiny amount of stuff that went into the pre-startup-sequence allocation is small enough that it will mostly run within the CPU caches anyway.

If rom mapping is being done by your CPU card's firmware it will probably go to its own native memory (fastest) anyway. The only card without local memory (A3640) doesn't have a built-in maprom feature so you'd use a software maprom tool that can come in startup-sequence after your memory priority tool.

No need to plug/unplug cards. Just use a memtest program on each range to figure out which is the fastest.
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Old 23 October 2019, 19:55   #6
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AmigaHope, maybe you mean 'before any AddMem'? Yes, if you have to run a command to make the Amiga see the RAM then it doesn't have to be resident, just before hte command that adds it.

If you mean MapROM, then not all of the performance is from libraries being mapped to RAM, and MapROM doesn't ask which card to use.

Unplugging cards is the failsafe and definitive method. If you have a program that speedtests only a memory range and the user knows 100% which range is which card, you can test each card. But ROM will (most likely) be mapped to the highest priority RAM, and that's what he's asking. Again, MapROM will not ask.

A MemTest is also not exactly the same as a performance speedtest. What you want to know if normal use will be faster or slower with a certain setup.
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