[Xen-users] Xen 4.1 on Debian Testing - missing memory

Alastair Sherringham
Wed, 03 Aug 2011 14:48:02 -0000

Hello,

I have installed Xen 4.1 on a server Tyan based server machine with
Debain Wheezy (testing) :

Linux 2.6.39-2-amd64
xen-hypervisor-4.1-amd64
4.1.1-1

The server has 8 dual-core AMD opterons and 8 GB RAM. It is a Tyan
S4881 motherboard and mezzanine board - 4+4 CPU''s.

On standard Linux, I see all 8 GB RAM.

On a plain install of Xen 4.1 (no configuration or guests), I see 5 GB
RAM. I assume something in the memory placement/map is causing this.

Is there anything I can do to see all 8 GB in Xen dom0? The BIOS has
some options for "node memory" interleaving, memory hole etc. but I am
not sure what to do.

I attach some log files and information showing the state.

1) dmesg - normal Linux
2) dmesg.xen - dmeg under Xen dom0
3) dmesg.xm - xm dmesg output in Xen dom0

And some memory information here. Any help or advice would be welcome.


Normal Linux :

# uname -a
Linux storserv1 2.6.39-2-amd64 #1 SMP Tue Jul 5 02:51:22 UTC 2011
x86_64 GNU/Linux

# free
             total       used       free     shared    buffers     cached
Mem:       8261616     317948    7943668          0      37108     165968
-/+ buffers/cache:     114872    8146744
Swap:      7811000          0    7811000

# cat /proc/meminfo
MemTotal:        8261616 kB
MemFree:         7943800 kB
Buffers:           37132 kB
Cached:           165964 kB
SwapCached:            0 kB
Active:           129904 kB
Inactive:          98524 kB
Active(anon):      25472 kB
Inactive(anon):      464 kB
Active(file):     104432 kB
Inactive(file):    98060 kB
Unevictable:           0 kB
Mlocked:               0 kB
SwapTotal:       7811000 kB
SwapFree:        7811000 kB
Dirty:                44 kB
Writeback:             0 kB
AnonPages:         25404 kB
Mapped:            11376 kB
Shmem:               588 kB
Slab:              33972 kB
SReclaimable:      14104 kB
SUnreclaim:        19868 kB
KernelStack:        1624 kB
PageTables:         3288 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:    11941808 kB
Committed_AS:      95920 kB
VmallocTotal:   34359738367 kB
VmallocUsed:       62116 kB
VmallocChunk:   34359666172 kB
HardwareCorrupted:     0 kB
AnonHugePages:         0 kB
HugePages_Total:       0
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB
DirectMap4k:       51776 kB
DirectMap2M:     8400896 kB


# cat /proc/mtrr
reg00: base=0x000000000 (    0MB), size= 2048MB, count=1: write-back
reg01: base=0x100000000 ( 4096MB), size= 4096MB, count=1: write-back
reg02: base=0x200000000 ( 8192MB), size= 1024MB, count=1: write-back
reg03: base=0x240000000 ( 9216MB), size=  512MB, count=1: write-back
reg04: base=0x080000000 ( 2048MB), size=  512MB, count=1: write-back
reg05: base=0x0c0000000 ( 3072MB), size=  256MB, count=1: write-combining

//////////////////////////////////////////////////////////////

Under Xen :

# uname -a
Linux storserv1 2.6.39-2-amd64 #1 SMP Tue Jul 5 02:51:22 UTC 2011
x86_64 GNU/Linux

# free
             total       used       free     shared    buffers     cached
Mem:       5029700     223128    4806572          0       8680      66008
-/+ buffers/cache:     148440    4881260
Swap:      7811000          0    7811000


# cat /proc/meminfo
MemTotal:        5029700 kB
MemFree:         4806456 kB
Buffers:            8680 kB
Cached:            65880 kB
SwapCached:            0 kB
Active:            69756 kB
Inactive:          52608 kB
Active(anon):      47824 kB
Inactive(anon):      548 kB
Active(file):      21932 kB
Inactive(file):    52060 kB
Unevictable:          52 kB
Mlocked:              52 kB
SwapTotal:       7811000 kB
SwapFree:        7811000 kB
Dirty:                 0 kB
Writeback:             0 kB
AnonPages:         48028 kB
Mapped:            12148 kB
Shmem:               564 kB
Slab:              30432 kB
SReclaimable:       8464 kB
SUnreclaim:        21968 kB
KernelStack:        1752 kB
PageTables:         3484 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:    10325848 kB
Committed_AS:     178724 kB
VmallocTotal:   34359738367 kB
VmallocUsed:       76620 kB
VmallocChunk:   34359654268 kB
HardwareCorrupted:     0 kB
AnonHugePages:         0 kB
HugePages_Total:       0
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB
DirectMap4k:     9697328 kB
DirectMap2M:           0 kB



--
Alastair Sherringham
http://www.sherringham.net




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