This isn't a software question so much as it is a hardware question.

I have an older Acer Aspire R1600. It came stock with 1MB of ram. I'm
running Debian Whezey on it.

Today I install 2 2GB dimms for a total of 4GB. However, when I do a top or
a memfree, it shows only 3GB.

total used free shared buffers cached
Mem: 3114340 619464 2494876 0 49556 459188
-/+ buffers/cache: 110720 3003620
Swap: 1830908 0 1830908

DMI Decode shows this:

Handle 0x0010, DMI type 17, 27 bytes
Array Handle: 0x000E
Size: 2048 MB
Speed: 800 MHz
Handle 0x0012, DMI type 17, 27 bytes
Array Handle: 0x000E
Size: 2048 MB
Speed: 800 MHz

Any thoughts as to why it only shows 3GB?

--- Mystic BBS v1.10 A52 (Linux)
* Origin: Cyberia BBS | Cyberia.Darktech.Org | Kingwood, TX

Hello Gryphon,

On 02 Nov 14 19:51, Gryphon wrote to All:

This isn't a software question so much as it is a hardware question.

I have an older Acer Aspire R1600. It came stock with 1MB of ram.
I'm running Debian Whezey on it.

Today I install 2 2GB dimms for a total of 4GB. However, when I do a
top or a memfree, it shows only 3GB.

total used free shared buffers
cached
Mem: 3114340 619464 2494876 0 49556
459188 -/+ buffers/cache: 110720 3003620
Swap: 1830908 0 1830908

DMI Decode shows this:

Handle 0x0010, DMI type 17, 27 bytes
Array Handle: 0x000E
Size: 2048 MB
Speed: 800 MHz
Handle 0x0012, DMI type 17, 27 bytes
Array Handle: 0x000E
Size: 2048 MB
Speed: 800 MHz

Any thoughts as to why it only shows 3GB?

My only thought would be that that's all the motherboard supports. Kind of like
my Athlon64 motherboard I'm using for my BBS machine. It has two dimm slots, but the most I can put in it is 2x1gb sticks of memory as it doesn't support any more than that. I can only assume if I were to put two 2gb sticks it would still read only 2gb of ram.

Regards,
Nick

--- GoldED+/LNX 1.1.5-b20130910
* Origin: thePharcyde_ telnet://bbs.pharcyde.org (Wisconsin) (723:1/701)
þ Synchronet þ thePharcyde_ telnet://bbs.pharcyde.org (Wisconsin)

On 11/02/14, Gryphon said the following...

This isn't a software question so much as it is a hardware question.

I have an older Acer Aspire R1600. It came stock with 1MB of ram. I'm running Debian Whezey on it.

Today I install 2 2GB dimms for a total of 4GB. However, when I do a
top or a memfree, it shows only 3GB.

32bit can't recognize over 3gig... you need 64bit for more... that or PAE capability i think...

the way i always tell if i need more memory in a machine is if swap space is being used... sometimes it is inevitable like when editing monstrous files
but genreally speaking, that's been my measure for years... i check usage
after a boot within minutes of everything being loaded and the system
settling down... if swap is being used then, then it may be time to add some memory... i also check again after a normal run of tasks but it can get sketchy...

--- Mystic BBS v1.10 A53 (Linux)
* Origin: Cyberia BBS | Cyberia.Darktech.Org | Kingwood, TX

On 11/03/14, wkitty42 said the following...

On 11/02/14, Gryphon said the following...

This isn't a software question so much as it is a hardware question.

I have an older Acer Aspire R1600. It came stock with 1MB of ram. I running Debian Whezey on it.

Today I install 2 2GB dimms for a total of 4GB. However, when I do a top or a memfree, it shows only 3GB.

32bit can't recognize over 3gig... you need 64bit for more... that or PAE capability i think...

Ok, I thought the upper limit was 4GB for 32-bit distros, not 3GB.

the way i always tell if i need more memory in a machine is if swap
space is being used... sometimes it is inevitable like when editing monstrous files but genreally speaking, that's been my measure for years... i check usage after a boot within minutes of everything being loaded and the system settling down... if swap is being used then, then
it may be time to add some memory... i also check again after a normal
run of tasks but it can get sketchy...

Well if performance begins to suck, even tho swap isn't being used, would
that point to a lack of memory, or would it be something else?

--- Mystic BBS v1.10 A53 (Linux)
* Origin: Cyberia BBS | Cyberia.Darktech.Org | Kingwood, TX

Re: Memory Usage
By: Gryphon to All on Sun Nov 02 2014 19:51:00

total used free shared buffers cached
Mem: 3114340 619464 2494876 0 49556
459188 -/+ buffers/cache: 110720 3003620
Swap: 1830908 0 1830908

Any thoughts as to why it only shows 3GB?

Not sure what type of system you're working with for sure, but I've seen top/procops output only show non-kernel occupied memory before. What's the size of your kernel memory?

---
þ Synchronet þ Tinfoil Tetrahedron BBS telnet or ssh -p 2222 to tinfoil.synchro.net

Re: Re: Memory Usage
By: Gryphon to wkitty42 on Mon Nov 03 2014 10:31 am

32bit processors can address 4GB of memory. Keep in mind that for some operating systems, video card memory is concatanated to the memory address space. So if you have a video card with 1GB of VRAM onboard, your available addressable main system memory decreases by 1GB. Also, any other DMA capable cards or chips in your system will subtract from the total available.

Xir
Sysop, Bayou Connection

---
þ Synchronet þ Bayou Connection - SHV - gumbo and gators, sometimes at the same meal

Re: Re: Memory Usage
By: wkitty42 to Gryphon on Mon Nov 03 2014 09:58:00

32bit can't recognize over 3gig... you need 64bit for more... that or PAE capability i think...

Memory addressing limitations never fall on odd numbered groups.

Taken from https://en.wikipedia.org/wiki/Memory_address

"while a 32-bit bus (e.g. Intel 80386) addresses 232 (4,294,967,296) locations, or a 4 GiB address space"

I'm gonna stick with what I said about it only showing userspace and daemon available RAM; the kernel is almost certainly what's gobbling up the rest, or maybe something having to do with BIOS.

---
þ Synchronet þ Tinfoil Tetrahedron BBS telnet or ssh -p 2222 to tinfoil.synchro.net

On 11/03/14, Gryphon said the following...

Ok, I thought the upper limit was 4GB for 32-bit distros, not 3GB.

remember that there's some address space that's reserved for the machine's use...

Well if performance begins to suck, even tho swap isn't being used, would that point to a lack of memory, or would it be something else?

it could be CPU contention or possibly waiting on the drives... running top
can generally show you these things... in top, i generally look to the "wa" percentage... if it is above a few percent then the machine is waiting on the drives... but generally speaking, it is likely CPU usage and tasks waiting on servicing...

--- Mystic BBS v1.10 A53 (Linux)
* Origin: Cyberia BBS | Cyberia.Darktech.Org | Kingwood, TX