Changing SWAP priority

A forum for Classic Amiga specific support issues.
ancalimon
Posts: 35
Joined: Tue Oct 18, 2011 7:31 am

Changing SWAP priority

Post by ancalimon »

How do I change the SWAP priority so that the SWAP partition on a spare 1000rpm hdd is used first instead of ZorRAM?

ZorRAM works when I'm simply copying stuff to RAM: but it kinda chokes when I try to delete the things that I copied. Also it is not working properly under load (for example when using OWB)

I guess I need to add something to bootloader command since I could not find any relevant option inside the 4000T kicklayout file.
User avatar
danbeaver
Posts: 367
Joined: Thu Jan 19, 2012 9:58 pm
Location: Someplace you'd rather not be
Contact:

Re: Changing SWAP priority

Post by danbeaver »

The system "knows" that Z3 RAM is faster than SWAP RAM and automatically uses it first. There is a way of changing the RAM priority ((Chip vs Fast) but I'm not sure it works the way you want. ZorRam is a slow down, but should not "Choke" on deletions; could you post some screen shots and be more explicit is exactly what is going on?
User avatar
DarrenHD
Beta Tester
Beta Tester
Posts: 635
Joined: Mon Dec 20, 2010 3:38 pm
Location: London, Ontario, Canada
Contact:

Re: Changing SWAP priority

Post by DarrenHD »

ancalimon wrote:How do I change the SWAP priority so that the SWAP partition on a spare 1000rpm hdd is used first instead of ZorRAM?

ZorRAM works when I'm simply copying stuff to RAM: but it kinda chokes when I try to delete the things that I copied. Also it is not working properly under load (for example when using OWB)

I guess I need to add something to bootloader command since I could not find any relevant option inside the 4000T kicklayout file.
Unfortunately the swap partition priority is hard-coded into the kernel - there is no way to change it. You would have no choice but to remove your ZorRAM. You can read the Classic_FAQ on the pros and cons of swap partitions on hard disks vs. ZorRAM.
AmigaOS 4.x Beta Tester - Classic Amiga enthusiast - http://www.hd-zone.com is my Amiga Blog, check it out!
Rotzloeffel
Posts: 35
Joined: Sat Jun 18, 2011 4:56 pm
Location: Wolfach / Germany

Re: Changing SWAP priority

Post by Rotzloeffel »

danbeaver wrote:The system "knows" that Z3 RAM is faster than SWAP RAM and automatically uses it first. There is a way of changing the RAM priority ((Chip vs Fast) but I'm not sure it works the way you want. ZorRam is a slow down, but should not "Choke" on deletions; could you post some screen shots and be more explicit is exactly what is going on?
First: Z3 Ram is limited by the Busterchip to 10-13 MB per second...... Cybervision SCSI have a speed of 36 to 38 MB/sec on my A3000T with a SSD-HD!
Second: There is no usefull software available using SWAP! OWB is not able to use SWAP it is a Programmers issue! Not the fault of the OS!

so at the end: SWAP is actually useless IMHO :ugeek: We don´t need SWAP, we need RAM! There is no difference using SLOW SWAP or using SLOW RAM....IMHO
User avatar
Thomas Frieden
AmigaOS Core Developer
AmigaOS Core Developer
Posts: 147
Joined: Fri Dec 10, 2010 3:21 pm

Re: Changing SWAP priority

Post by Thomas Frieden »

Rotzloeffel wrote: so at the end: SWAP is actually useless IMHO :ugeek: We don´t need SWAP, we need RAM! There is no difference using SLOW SWAP or using SLOW RAM....IMHO
IMHO ?

This isn't an issue of opinion, but of fact. You are leaving out the most important part in the equation, that of latency, which is HORRIBLE on chip ram, mainbaord ram, or any Z3 ram. When each and every access to memory requires 4 to 5 wait states, the memory becomes unusable.

For giggles, I once tried running code from mainboard memory. Was just outputting stuff to the console... Remember those old 300 baud acoustic couplers ? Those were faster than this...
alekc
Posts: 50
Joined: Sat Jun 18, 2011 3:06 pm

Re: Changing SWAP priority

Post by alekc »

Thomas Frieden wrote:
Rotzloeffel wrote: so at the end: SWAP is actually useless IMHO :ugeek: We don´t need SWAP, we need RAM! There is no difference using SLOW SWAP or using SLOW RAM....IMHO
IMHO ?

This isn't an issue of opinion, but of fact. You are leaving out the most important part in the equation, that of latency, which is HORRIBLE on chip ram, mainbaord ram, or any Z3 ram. When each and every access to memory requires 4 to 5 wait states, the memory becomes unusable.
So maybe the manual for AmigaOS 4.1 Classic should be updated to reflect this info?
User avatar
danbeaver
Posts: 367
Joined: Thu Jan 19, 2012 9:58 pm
Location: Someplace you'd rather not be
Contact:

Re: Changing SWAP priority

Post by danbeaver »

Folks, if you check the threads in this forum on RAM access speed, this has all been discussed ad nauseam with all the numbers, including ways to free up more ram and crazy ideas like making a ram board for the CSPPC's PCI slot.
Rotzloeffel
Posts: 35
Joined: Sat Jun 18, 2011 4:56 pm
Location: Wolfach / Germany

Re: Changing SWAP priority

Post by Rotzloeffel »

Thomas Frieden wrote: IMHO ?

This isn't an issue of opinion, but of fact.
Yes, you are right :roll:
Thomas Frieden wrote: You are leaving out the most important part in the equation, that of latency, which is HORRIBLE on chip ram, mainbaord ram, or any Z3 ram. When each and every access to memory requires 4 to 5 wait states, the memory becomes unusable.

For giggles, I once tried running code from mainboard memory. Was just outputting stuff to the console... Remember those old 300 baud acoustic couplers ? Those were faster than this...
Thanks Thomas! This is the FIRST time ever I got an explanation of the problem! I only heard it is slow, but I had no idea why and how slow it is... so thanks again.
ancalimon
Posts: 35
Joined: Tue Oct 18, 2011 7:31 am

Re: Changing SWAP priority

Post by ancalimon »

So do you think it would be a good idea to use OS4.1 on my A1200 instead of 4000T because of this memory limitation.
User avatar
danbeaver
Posts: 367
Joined: Thu Jan 19, 2012 9:58 pm
Location: Someplace you'd rather not be
Contact:

Re: Changing SWAP priority

Post by danbeaver »

The BlizzardPPC has other issues that outweigh the amount of available RAM between the A1200 and the A4000T. I never ran out of ram on my A4T unless I tried to by running huge memory hogs at the same time. If you think you really need that much ram, just buy an NG Amiga; they can access 2 GB at present with the even more as paged ram in the near future (info on this is also in the forums).
Post Reply