Arch Linux

adam17

Member

Registered: 2016-12-03

Posts: 3

Memory Reported Less than Installed

Hi All,

I have a 12 memory slots, all 8GB, total 96 GB.
Bios can correctly see the 12 slots with a total of 96 GB.

In Archlinux, it can see the 12 slots again.
However, when running free, it reports 82GB only.
No errors on booting, or dmesg.

Details:

Linux 4.8.10-1-ARCH #1 SMP PREEMPT Mon Nov 21 11:55:43 CET 2016 x86_64 GNU/Linux

sudo dmidecode -t memory|grep Size
        Size: 8192 MB
        Size: 8192 MB
        Size: 8192 MB
        Size: 8192 MB
        Size: 8192 MB
        Size: 8192 MB
        Size: 8192 MB
        Size: 8192 MB
        Size: 8192 MB
        Size: 8192 MB
        Size: 8192 MB
        Size: 8192 MB

sudo dmidecode -t memory|grep  Locator
        Locator: DIMM 1
        Bank Locator: Not Specified
        Locator: DIMM 2
        Bank Locator: Not Specified
        Locator: DIMM 3
        Bank Locator: Not Specified
        Locator: DIMM 4
        Bank Locator: Not Specified
        Locator: DIMM 5
        Bank Locator: Not Specified
        Locator: DIMM 6
        Bank Locator: Not Specified
        Locator: RISER DIMM 1
        Bank Locator: Not Specified
        Locator: RISER DIMM 2
        Bank Locator: Not Specified
        Locator: RISER DIMM 3
        Bank Locator: Not Specified
        Locator: RISER DIMM 4
        Bank Locator: Not Specified
        Locator: RISER DIMM 5
        Bank Locator: Not Specified
        Locator: RISER DIMM 6
        Bank Locator: Not Specified

free
              total        used        free      shared  buff/cache   available
Mem:       82487296     4143336    76240400       89792     2103560    77395452
Swap:       4194300           0     4194300

Thanks,

Adam,

ewaller

Administrator

From: Pasadena, CA

Registered: 2009-07-13

Posts: 19,792

Re: Memory Reported Less than Installed

96GB.  Let me just ponder that for a second.  My first computer had a whooping 1k of RAM.  That is a ratio of almost 100 million : 1.  Sweet Jesu.

In any event, I would look through the journal for clues.  TBH, I've not worked with more than 16GB so I don't know what monsters lurk beyond that limit

Edit:  Oh, BTW:  Welcome to the Arch Linux forums

Last edited by ewaller (2016-12-03 16:10:57)

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seth

Member

Registered: 2012-09-03

Posts: 51,253

Re: Memory Reported Less than Installed

rule out a bug in free: "cat /proc/meminfo"
Check dmesg for "BIOS-e820" (ie. whether the BIOS/UEFI takes a bigger share, like for an IGP)

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adam17

Member

Registered: 2016-12-03

Posts: 3

Re: Memory Reported Less than Installed

Thanks Seth for your reply.

cat /proc/meminfo
MemTotal:       82487296 kB
MemFree:        64473212 kB
MemAvailable:   69283556 kB
Buffers:            2104 kB
Cached:          5299040 kB
SwapCached:            0 kB
Active:         10064700 kB
Inactive:        3195924 kB
Active(anon):    7961608 kB
Inactive(anon):   138276 kB
Active(file):    2103092 kB
Inactive(file):  3057648 kB
Unevictable:           0 kB
Mlocked:               0 kB
SwapTotal:       4194300 kB
SwapFree:        4194300 kB
Dirty:               168 kB
Writeback:             0 kB
AnonPages:       7934300 kB
Mapped:           450356 kB
Shmem:            140404 kB
Slab:            2833300 kB
SReclaimable:     508312 kB
SUnreclaim:      2324988 kB
KernelStack:       17360 kB
PageTables:        51484 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:    45437948 kB
Committed_AS:   15486688 kB
VmallocTotal:   34359738367 kB
VmallocUsed:           0 kB
VmallocChunk:          0 kB
HardwareCorrupted:     0 kB
AnonHugePages:   6451200 kB
ShmemHugePages:        0 kB
ShmemPmdMapped:        0 kB
HugePages_Total:       0
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB
DirectMap4k:      962532 kB
DirectMap2M:    18958336 kB
DirectMap1G:    66060288 kB

BIOS-e820:

[    0.000000] e820: BIOS-provided physical RAM map:
[    0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009dbff] usable
[    0.000000] BIOS-e820: [mem 0x00000000000f0000-0x00000000000fffff] reserved
[    0.000000] BIOS-e820: [mem 0x0000000000100000-0x00000000bfdf9bff] usable
[    0.000000] BIOS-e820: [mem 0x00000000bfdf9c00-0x00000000bfe4bbff] ACPI NVS
[    0.000000] BIOS-e820: [mem 0x00000000bfe4bc00-0x00000000bfe4dbff] ACPI data
[    0.000000] BIOS-e820: [mem 0x00000000bfe4dc00-0x00000000bfffffff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000f8000000-0x00000000fcffffff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000fe000000-0x00000000fed003ff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000fee00000-0x00000000feefffff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000ffb00000-0x00000000ffffffff] reserved
[    0.000000] BIOS-e820: [mem 0x0000000100000000-0x000000143fffffff] usable
[    0.000000] e820: update [mem 0x00000000-0x00000fff] usable ==> reserved
[    0.000000] e820: remove [mem 0x000a0000-0x000fffff] usable
[    0.000000] e820: last_pfn = 0x1440000 max_arch_pfn = 0x400000000
[    0.000000] e820: last_pfn = 0xbfdf9 max_arch_pfn = 0x400000000
[    0.000000] e820: [mem 0xc0000000-0xf7ffffff] available for PCI devices
[    2.640362] PCI: MMCONFIG at [mem 0xf8000000-0xfbffffff] reserved in E820
[    2.973391] e820: reserve RAM buffer [mem 0x0009dc00-0x0009ffff]
[    2.973391] e820: reserve RAM buffer [mem 0xbfdf9c00-0xbfffffff]

Is this a bug ?

Regards,

Last edited by adam17 (2016-12-03 17:14:25)

mich41

Member

Registered: 2012-06-22

Posts: 796

Re: Memory Reported Less than Installed

Your BIOS reports exactly 80GB of RAM (0x143fffffff is spot on 81GB, subtract 1GB hole from 0xc0000000 to 0xffffffff).

How much RAM is reported in BIOS setup? How much assigned to the GPU (if any)? Is it UEFI? What hardware?

adam17

Member

Registered: 2016-12-03

Posts: 3

Re: Memory Reported Less than Installed

Hi Mich41,

Thanks for your reply.

The bios was showing 12 Dims with 8GB each.
I removed all the memory  modules, then installed them again.

Now, the OS is showing :

            total        used        free      shared  buff/cache   available
Mem:       99002360     2155576    95848052      101612      998732    95880388
Swap:       4194300           0     4194300

which is 94G.

Meminfo:

MemTotal:       99002360 kB
MemFree:        95627432 kB
MemAvailable:   95902140 kB
Buffers:            2104 kB
Cached:          1139632 kB
SwapCached:            0 kB
Active:          1320352 kB
Inactive:         690440 kB
Active(anon):     882036 kB
Inactive(anon):    74524 kB
Active(file):     438316 kB
Inactive(file):   615916 kB
Unevictable:           0 kB
Mlocked:               0 kB
SwapTotal:       4194300 kB
SwapFree:        4194300 kB
Dirty:               100 kB
Writeback:             0 kB
AnonPages:        867012 kB
Mapped:           302828 kB
Shmem:             87504 kB
Slab:             328784 kBRegards and
SReclaimable:      86396 kB
SUnreclaim:       242388 kB
KernelStack:       12080 kB
PageTables:        23976 kB
NFS_Unstable:          0 kBthat
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:    53695480 kB
Committed_AS:    3574220 kB
VmallocTotal:   34359738367 kB
VmallocUsed:           0 kB
VmallocChunk:          0 kB
HardwareCorrupted:     0 kB
AnonHugePages:    268288 kB
ShmemHugePages:        0 kB
ShmemPmdMapped:        0 kB
HugePages_Total:       0
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB
DirectMap4k:      518116 kB
DirectMap2M:     5771264 kB
DirectMap1G:    96468992 kB

This is on a Dell Precision T7500.

I guess this should be correct!

Thanks all for your prompt replies,

:-D

jasonwryan

Anarchist

From: .nz

Registered: 2009-05-09

Posts: 30,424

Website

Re: Memory Reported Less than Installed

Please use code tags when pasting to the boards: https://wiki.archlinux.org/index.php/Co … s_and_code

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mich41

Member

Registered: 2012-06-22

Posts: 796

Re: Memory Reported Less than Installed

The bios was showing 12 Dims with 8GB each.

The problem is that depending on BIOS quality, this may or may not reflect how many DIMMs have actually been enabled

A more reliable figure is "total available memory", sometimes shown somewhere in general setup. This should be closer to what gets reported to the OS.

94.4G is OK for a 96GB machine - AFAIK the kernel uses 1/64 of all RAM to keep track what's in the remaining 63/64 (may be a different number on 32bits) and this memory is not listed by free.

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