Trying to understand reported RAM

[Barkingmad]

Hello

I am trying to understand this for interest really as things are working OK.

I have recently scored some RAM modules for my P4 box to fill out all the m'board slots.

The BIOS agrees with what's physically there - 1GB in each of 4 slots, 4GB total.

I try booting a Bionic 64 CD so I can see the 64bit kernel report all 4GB but find the RAM number in htop starting with a 3, what gives? I think.
I find pup-sysinfo and the report for RAM is similar I have attached the report but the anomaly I'm trying to understand is this:

Physical RAM, at the bottom of the report, agrees with the BIOS - 4 slots 1024MB in each 4GB total.
Total RAM, near the top, says 3254MB. My calculator says 4X1024=4096 so where has the other 842MB got to?

The mainboard is Intel 945 based with no onboard graphics, I have a PCIe card with it's own VRAM.

The other thing is that Taha 32 reports similar, though not quite the same, numbers where I only expected to see 2GB recognized - is Taha PAE based?

Thanks for any enlightenment.
Will

[bigpup]

The problem may occur because some BIOS settings are incorrect.
Check the BIOS settings to see whether the memory remapping feature is enabled.
May call it something else.
This can be listed as memory remapping, memory extension, or something similar.
Anyway, look in the computers bios setup for settings for memory.

Do you know how to boot into the bios setup?

[bigpup]

The other thing is that Taha 32 reports similar, though not quite the same, numbers where I only expected to see 2GB recognized - is Taha PAE based?

What specific Puppy version you asking about?
What is the name of the Puppy version iso?
Taha 32 tells us nothing???

[Barkingmad]

Hello Bigpup

Thanks for replying, I'll answer in reverse order as I thing it will be clearer.

Taha version is 606 but looking again at pup-sysinfo I think has answered my question

Code: Select all

Linux Kernel: 3.14.79 (i686)
Kernel Version: #1 SMP PREEMPT Tue Dec 13 19:32:40 GMT 2016
PAE Enabled: No

pasted from "distro-specs" looks clear enough.

As to why a 64bit pup (Bionic64) doesn't report all 4GB.

I've looked all round in the BIOS and the only options I can find for memory are for the SPD timings which are set to Auto, the correct module sizes are reported for each slot and total, as I say, 4GB. The board is an Intel D945PSN, info is still available from Intel https://www.intel.co.uk/content/www/uk/ ... oards.html
Rereading the user guide though I might have found the answer

NOTE
System resources (such as PCI and PCI Express) require physical memory address locations that
reduce available memory addresses above 3 GB. This may result in less than 4 GB of memory
being available to the operating system and applications.

There is no further info on this but looks as though there is a similar limit in hardware as we see with 32bit OS. I would be interested to hear from anyone with better hardware knowhow then me about this.

Thanks for your help and any further contributions welcome.
Will

[bigpup]

That note may be the answer.
Some memory is being used by the motherboard and not being released to the operating system.

In the bios is there anyplace that offers ability to enable the "memory hole"?

[puppy_apprentice]

The mainboard is Intel 945 based with no onboard graphics, I have a PCIe card with it's own VRAM.

In my old computer BIOS there was an option to give GPU extra ram even if GPU was in AGP slot. Those memory GPU could use for better textures.

AGP aperture size

[Barkingmad]

Thanks

I have been all through the BIOS settings and there are no user options to allocate memory to anything. Also, when I had 2GB installed that's what was reported in all OS without any being "creamed off"

All I can suppose is that the memory controller can only address 4GB and this shows up with a full 4GB of general RAM installed because the "top" addresses are already in use for graphics card, processor cache etc.

I don't think this is worth spending much more time on as the increase I have achieved is useful and the modules were being offered free on another forum I use

Thanks all.
Will

[rcrsn51]

... but find the RAM number in htop starting with a 3 ...

Is that value in MB or in MiB?

A MiB is calculated in powers of 2 and is slightly larger than a MB, which is in powers of 10.

So total memory expressed in MiB will be slightly less than in MB.

My machine has 4GB of RAM, but top reports "MiB Mem : 3820.9"

By analogy, an inch is bigger than a cm. So measuring something in inches will give a smaller number than when measured in cm.

[puppy_apprentice]

You can check free command in terminal.

[rockedge]

I tend to use the -h | --human operator to get a quick understanding of the RAM situation:

Screenshot(6).png (13.23 KiB) Viewed 263 times

[puppy_apprentice]

busybox free gives only option -g (giga) but it rounds to integer, better is -m (mega).