PVE Host Swaps, when it has a lot of memory available

R

RRJ

Member
Apr 14, 2010
245
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16
Estonia, Tallinn
Hi,

Just noticed, that proxmox Host PVE swaps, when it has a lot of memory. /proc/userbeancounters fails show 0 for every host. Why this could happen?

Memory usage is like: committed 7, total 14, swaped 1,5 GB.

Code: 
pve-manager: 2.2-26 (pve-manager/2.2/c1614c8c)
running kernel: 2.6.32-16-pve
proxmox-ve-2.6.32: 2.2-80
pve-kernel-2.6.32-11-pve: 2.6.32-66
pve-kernel-2.6.32-16-pve: 2.6.32-80
lvm2: 2.02.95-1pve2
clvm: 2.02.95-1pve2
corosync-pve: 1.4.4-1
openais-pve: 1.1.4-2
libqb: 0.10.1-2
redhat-cluster-pve: 3.1.93-1
resource-agents-pve: 3.9.2-3
fence-agents-pve: 3.1.9-1
pve-cluster: 1.0-28
qemu-server: 2.0-64
pve-firmware: 1.0-21
libpve-common-perl: 1.0-37
libpve-access-control: 1.0-25
libpve-storage-perl: 2.0-34
vncterm: 1.0-3
vzctl: 4.0-1pve2
vzprocps: 2.0.11-2
vzquota: 3.1-1
pve-qemu-kvm: 1.2-7
ksm-control-daemon: 1.1-1

Processes sorted by SWAP usage:
Code: 
    PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  SWAP COMMAND
   7446 root      20   0 1283m 404m 1984 S    5  2.9   5106:54 879m kvm
 260223 root      20   0  773m  70m 2412 S    4  0.5   5218:39 703m kvm
   6893 root      20   0  871m 367m 2412 S    2  2.6   5030:06 504m kvm
   7541 root      20   0  580m  81m 2412 S    3  0.6   5155:20 499m kvm
   7617 root      20   0  863m 370m 2424 S    6  2.6   7540:55 492m kvm
   5706 root      20   0  640m 235m 2412 S    3  1.7   4771:37 405m kvm
   1531 root      20   0  381m 1364  828 S    0  0.0  56:50.17 380m rrdcached
   7382 root      20   0 1064m 703m 2420 S   24  5.0  32478:19 360m kvm
   1554 root      20   0  336m  19m  18m S    1  0.1 325:48.87 317m pmxcfs
 854368 www-data  20   0  294m 5436 1496 S    0  0.0   0:00.17 289m apache2
 854367 www-data  20   0  293m 5428 1492 S    0  0.0   0:00.18 288m apache2

If I go inside a KVM Guest, I don't see any SWAP usage nor high memory usage.

As an example, the free output from machine that runs under process PID 260223
Code: 
             total       used       free     shared    buffers     cached
Mem:        767512     694528      72984          0      99384     245136
-/+ buffers/cache:     350008     417504
Swap:      1048568         92    1048476
 
Last edited:
RRJ said:
Hi,

Just noticed, that proxmox Host PVE swaps, when it has a lot of memory. /proc/userbeancounters fails show 0 for every host. Why this could happen?

Memory usage is like: committed 7, total 14, swaped 1,5 GB.

Code: 
pve-manager: 2.2-26 (pve-manager/2.2/c1614c8c)
running kernel: 2.6.32-16-pve
proxmox-ve-2.6.32: 2.2-80
pve-kernel-2.6.32-11-pve: 2.6.32-66
pve-kernel-2.6.32-16-pve: 2.6.32-80
lvm2: 2.02.95-1pve2
clvm: 2.02.95-1pve2
corosync-pve: 1.4.4-1
openais-pve: 1.1.4-2
libqb: 0.10.1-2
redhat-cluster-pve: 3.1.93-1
resource-agents-pve: 3.9.2-3
fence-agents-pve: 3.1.9-1
pve-cluster: 1.0-28
qemu-server: 2.0-64
pve-firmware: 1.0-21
libpve-common-perl: 1.0-37
libpve-access-control: 1.0-25
libpve-storage-perl: 2.0-34
vncterm: 1.0-3
vzctl: 4.0-1pve2
vzprocps: 2.0.11-2
vzquota: 3.1-1
pve-qemu-kvm: 1.2-7
ksm-control-daemon: 1.1-1

Processes sorted by SWAP usage:
Code: 
    PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  SWAP COMMAND
   7446 root      20   0 1283m 404m 1984 S    5  2.9   5106:54 879m kvm
 260223 root      20   0  773m  70m 2412 S    4  0.5   5218:39 703m kvm
   6893 root      20   0  871m 367m 2412 S    2  2.6   5030:06 504m kvm
   7541 root      20   0  580m  81m 2412 S    3  0.6   5155:20 499m kvm
   7617 root      20   0  863m 370m 2424 S    6  2.6   7540:55 492m kvm
   5706 root      20   0  640m 235m 2412 S    3  1.7   4771:37 405m kvm
   1531 root      20   0  381m 1364  828 S    0  0.0  56:50.17 380m rrdcached
   7382 root      20   0 1064m 703m 2420 S   24  5.0  32478:19 360m kvm
   1554 root      20   0  336m  19m  18m S    1  0.1 325:48.87 317m pmxcfs
 854368 www-data  20   0  294m 5436 1496 S    0  0.0   0:00.17 289m apache2
 854367 www-data  20   0  293m 5428 1492 S    0  0.0   0:00.18 288m apache2

If I go inside a KVM Guest, I don't see any SWAP usage nor high memory usage.

As an example, the free output from machine that runs under process PID 260223
Code: 
             total       used       free     shared    buffers     cached
Mem:        767512     694528      72984          0      99384     245136
-/+ buffers/cache:     350008     417504
Swap:      1048568         92    1048476
Click to expand...
Hi,
are you sure that the host swaps?
If I look on a host, there is some swap-space used but not realy swaping:
Code: 
root@proxmox1:~# swapon -s
Filename                                Type            Size    Used    Priority
/dev/dm-29                              partition       8388600 13544   -1
root@proxmox1:~# iostat -dm 5 dm-29
Linux 2.6.32-17-pve (proxmox1)  02/05/2013      _x86_64_        (8 CPU)

Device:            tps    MB_read/s    MB_wrtn/s    MB_read    MB_wrtn
dm-29             0.51         0.00         0.00       6631         44

Device:            tps    MB_read/s    MB_wrtn/s    MB_read    MB_wrtn
dm-29             0.00         0.00         0.00          0          0

Device:            tps    MB_read/s    MB_wrtn/s    MB_read    MB_wrtn
dm-29             1.00         0.00         0.00          0          0

Device:            tps    MB_read/s    MB_wrtn/s    MB_read    MB_wrtn
dm-29             0.00         0.00         0.00          0          0
^C
root@proxmox1:~# cat /proc/meminfo 
MemTotal:       32889844 kB
MemFree:          195576 kB
Buffers:          360280 kB
Cached:         14026968 kB
SwapCached:         1492 kB
Active:         17666456 kB
Inactive:       14240992 kB
Active(anon):   16454096 kB
Inactive(anon):  1124116 kB
Active(file):    1212360 kB
Inactive(file): 13116876 kB
Unevictable:       63740 kB
Mlocked:           63740 kB
SwapTotal:       8388600 kB
SwapFree:        8375056 kB
Dirty:               536 kB
Writeback:             0 kB
AnonPages:      17582560 kB
Mapped:            72372 kB
Shmem:             51480 kB
Slab:             356924 kB
SReclaimable:     293188 kB
SUnreclaim:        63736 kB
KernelStack:        3456 kB
PageTables:        53508 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:    24833520 kB
Committed_AS:   23378076 kB
VmallocTotal:   34359738367 kB
VmallocUsed:      432892 kB
VmallocChunk:   34359151040 kB
HardwareCorrupted:     0 kB
AnonHugePages:         0 kB
HugePages_Total:       0
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB
DirectMap4k:        7168 kB
DirectMap2M:     2039808 kB
DirectMap1G:    31457280 kB
BTW. swapping inside an KVM-guest has nothing to do with swapping of the host.

Udo
 
Well, it does not actually swap. May be I asked my question in wrong way. Just interesting, what could be the reason for moving data to disk (swap), when it has a lot of memory to use. And actually, if data was placed there, it will be read someday too and this reading will be slow.
 
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