• Memory Usage

    From Gryphon@VERT to All on Sun Nov 2 19:51:00 2014
    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
  • From Access Denied@VERT to Gryphon on Sun Nov 2 21:35:40 2014
    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

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  • From wkitty42@VERT to Gryphon on Mon Nov 3 09:58:00 2014
    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 | Kingw
  • From Gryphon@VERT to wkitty42 on Mon Nov 3 10:31:00 2014
    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
  • From Khelair@VERT to Gryphon on Mon Nov 3 06:15:27 2014
    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?

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  • From Xir@VERT to Gryphon on Mon Nov 3 13:26:47 2014
    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

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    Synchronet
  • From Khelair@VERT to wkitty42 on Mon Nov 3 15:18:00 2014
    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.

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  • From wkitty42@VERT to Gryphon on Mon Nov 3 20:49:00 2014
    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 |