Ubuntu

Less then 1GB of memory dected with generic kernel but server kernel detects full 2GB

Asked by Josh Hoppes

I'm not sure what's going on but while I can see the generic kernel config has the CONFIG_HIGHMEM4G option enabled it's only detecting 986M of RAM. Oddly enough if I install and run the linux-server kernel package it detects the full 2GB of RAM I have installed but I'm having a hard time figuring out why this is happening as I have never seen this issue before with any other distribution. Here is the CPU info in case it helps, I'm kind of at a loss.

processor : 0
vendor_id : AuthenticAMD
cpu family : 15
model : 15
model name : AMD Athlon(tm) 64 Processor 3500+
stepping : 0
cpu MHz : 1000.000
cache size : 512 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx mmxext lm 3dnowext 3dnow up ts fid vid ttp
bogomips : 2045.51
clflush size : 64

Question information

Language:
English Edit question
Status:
Solved
For:
Ubuntu Edit question
Assignee:
No assignee Edit question
Solved by:
Josh Hoppes
Solved:
Last query:
Last reply:
Revision history for this message
Selene ToyKeeper (toykeeper) said : 		#1

Could you provide the output of "uname -a" on both the working kernel and the broken kernel? Also, it may be helpful to see the contents of /proc/cmdline and /proc/meminfo for both.

I'm not certain, but it looks like you may be running a 32-bit kernel on a 64-bit machine. If that is the case, I recommend switching to the 64-bit version of Ubuntu.

However, the missing memory may still be a bug worth investigating, if you have time to provide data and/or try some experiments.

Revision history for this message
Christophe Painchaud (dash-ionblast) said : 		#2

Also be careful with AGP/PCI-Express shared memory for graphic card !

Revision history for this message
Josh Hoppes (jvhoppes) said : 		#3

Here is the info Scott asked for. I agree an easy fix probably would be to just switch to the x86-64 kernel, how ever I'm unsure of how the compatibility issues with Firefox plugins has come along at this point in time hence why I didn't go with that when I installed initially.

As for my graphics card it's an nVidia 6800 GT AGP, doesn't use shared memory and my AGP aperture size is only 32MB

For the working kernel
Linux spawn 2.6.24-16-server #1 SMP Thu Apr 10 13:58:00 UTC 2008 i686 GNU/Linux
root=UUID=66ed938d-eb4a-4299-be0c-792896cf08e2 ro quiet splash
MemTotal: 2074580 kB
MemFree: 1862544 kB
Buffers: 10032 kB
Cached: 134176 kB
SwapCached: 0 kB
Active: 82292 kB
Inactive: 102240 kB
HighTotal: 1178560 kB
HighFree: 996252 kB
LowTotal: 896020 kB
LowFree: 866292 kB
SwapTotal: 2955920 kB
SwapFree: 2955920 kB
Dirty: 76 kB
Writeback: 0 kB
AnonPages: 40324 kB
Mapped: 18272 kB
Slab: 13596 kB
SReclaimable: 6420 kB
SUnreclaim: 7176 kB
PageTables: 1332 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
CommitLimit: 3993208 kB
Committed_AS: 65680 kB
VmallocTotal: 118776 kB
VmallocUsed: 6748 kB
VmallocChunk: 111596 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB

For the broken kernel
Linux spawn 2.6.24-16-generic #1 SMP Thu Apr 10 13:23:42 UTC 2008 i686 GNU/Linux
root=UUID=66ed938d-eb4a-4299-be0c-792896cf08e2 ro quiet splash
MemTotal: 1009756 kB
MemFree: 194576 kB
Buffers: 21296 kB
Cached: 506852 kB
SwapCached: 0 kB
Active: 441524 kB
Inactive: 321476 kB
HighTotal: 129984 kB
HighFree: 3880 kB
LowTotal: 879772 kB
LowFree: 190696 kB
SwapTotal: 2955920 kB
SwapFree: 2955920 kB
Dirty: 15236 kB
Writeback: 0 kB
AnonPages: 234904 kB
Mapped: 80996 kB
Slab: 26656 kB
SReclaimable: 16240 kB
SUnreclaim: 10416 kB
PageTables: 2104 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
CommitLimit: 3460796 kB
Committed_AS: 744284 kB
VmallocTotal: 114680 kB
VmallocUsed: 48504 kB
VmallocChunk: 61428 kB

Revision history for this message
Josh Hoppes (jvhoppes) said : 		#4

Linux spawn 2.6.24-16-generic #1 SMP Thu Apr 10 13:23:42 UTC 2008 i686 GNU/Linux

MemTotal: 2074740 kB
MemFree: 1536740 kB
Buffers: 14288 kB
Cached: 285980 kB
SwapCached: 0 kB
Active: 287748 kB
Inactive: 205520 kB
HighTotal: 1178560 kB
HighFree: 683112 kB
LowTotal: 896180 kB
LowFree: 853628 kB
SwapTotal: 2955920 kB
SwapFree: 2955920 kB
Dirty: 40 kB
Writeback: 0 kB
AnonPages: 193000 kB
Mapped: 65728 kB
Slab: 19592 kB
SReclaimable: 10760 kB
SUnreclaim: 8832 kB
PageTables: 1912 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
CommitLimit: 3993288 kB
Committed_AS: 697564 kB
VmallocTotal: 114680 kB
VmallocUsed: 48504 kB
VmallocChunk: 61428 kB
xipher@spawn:~$ cat /proc/cpuinfo
processor : 0
vendor_id : AuthenticAMD
cpu family : 15
model : 15
model name : AMD Athlon(tm) 64 Processor 3500+
stepping : 0
cpu MHz : 1000.000
cache size : 512 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx mmxext lm 3dnowext 3dnow up ts fid vid ttp
bogomips : 2045.53
clflush size : 64

root=UUID=66ed938d-eb4a-4299-be0c-792896cf08e2 ro quiet splash

free -m
             total used free shared buffers cached
Mem: 2026 525 1500 0 13 279
-/+ buffers/cache: 232 1793
Swap: 2886 0 2886

All of a sudden with the last round of updates the kernel is detecting the full 2GB. No update to the kernel at all but something must have effected it in the latest round that "fixed" the problem