Messages in this thread | | | Date | Sat, 02 Jun 2007 10:51:12 +0200 | From | Eric Dumazet <> | Subject | Re: Missing RAM on x86_64 |
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Mike Richards a écrit : > Hi, I appear to be missing quite a bit of RAM on an x86_64 system. I > have 1GB installed, but 'free' only shows 878MB: > > pokey$ free -m > total used free shared buffers cached > Mem: 878 571 306 0 52 332 > -/+ buffers/cache: 186 691 > Swap: 1023 0 1023 > > I'm used to seeing a little bit of RAM missing with 32bit systems, but > 146MB seems a bit much. The part of dmesg that concerns the RAM is > shown below. Anyone know what's up here? Is this normal for an x86_64 > system? > > Linux version 2.6.20.11 (root@pokey) (gcc version 4.1.2) #1 SMP Thu > May 24 18:29:52 GMT 2007 > Command line: auto BOOT_IMAGE=2.6.20.11 rw root=801 > BIOS-provided physical RAM map: > BIOS-e820: 0000000000000000 - 000000000009fc00 (usable) > BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved) > BIOS-e820: 00000000000e0000 - 0000000000100000 (reserved) > BIOS-e820: 0000000000100000 - 0000000037fd0000 (usable) > BIOS-e820: 0000000037fd0000 - 0000000037fde000 (ACPI data) > BIOS-e820: 0000000037fde000 - 0000000038000000 (ACPI NVS) > BIOS-e820: 00000000fec00000 - 00000000fec01000 (reserved) > BIOS-e820: 00000000fee00000 - 00000000fef00000 (reserved) > BIOS-e820: 00000000ff780000 - 0000000100000000 (reserved)
I would say your BIOS needs an update or some tweakings.
The (usable) parts that it gives to the OS (linux) are :
0000000000000000 - 000000000009fc00 0000000000100000 - 0000000037fd0000
Thats not 1024 MB, but 892 MB
Here is the output on a 16 GB x86_64 machine
BIOS-provided physical RAM map: BIOS-e820: 0000000000000000 - 000000000009fc00 (usable) BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved) BIOS-e820: 00000000000e0000 - 0000000000100000 (reserved) BIOS-e820: 0000000000100000 - 000000007fff0000 (usable) BIOS-e820: 000000007fff0000 - 000000007ffff000 (ACPI data) BIOS-e820: 000000007ffff000 - 0000000080000000 (ACPI NVS) BIOS-e820: 00000000ff780000 - 0000000100000000 (reserved) BIOS-e820: 0000000100000000 - 0000000480000000 (usable)
On node 0 totalpages: 2097039 On node 1 totalpages: 2097152
total of 4194078 pages (while exact 16GB should be 4194304 pages)
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