[Kernelfeatures-devel] high memory usage and hugepage setting

[Marco Giovannini]

Hi guys

I'm using Oracle Linux Server release 6.4 with UEK kernel
2.6.39-400.209.1.el6uek.x86_64.

I saw in config file of the kernel that UEK does not use trasparent huge
page.

# CONFIG_TRANSPARENT_HUGEPAGE is not set

This is not a issue for me as I'm running Oracle RAC and I could not use it
anyway :)

My current setting kernel setting for RAC are provided using the oracle
package 'oracle-rdbms-server-11gR2-preinstall-1.0-7.el6.x86_64' + some
additional conf added manually

net.ipv4.ip_forward = 0
net.ipv4.conf.default.rp_filter = 0
net.ipv4.conf.default.accept_source_route = 0
kernel.sysrq = 0
kernel.core_uses_pid = 1
net.ipv4.tcp_syncookies = 1
net.bridge.bridge-nf-call-ip6tables = 0
net.bridge.bridge-nf-call-iptables = 0
net.bridge.bridge-nf-call-arptables = 0
kernel.msgmnb = 65536
kernel.msgmax = 65536
fs.file-max = 6815744
kernel.sem = 250 32000 100 128
kernel.shmmni = 4096
kernel.shmall = 1073741824
kernel.shmmax = 4398046511104
net.core.rmem_default = 262144
net.core.rmem_max = 4194304
net.core.wmem_default = 262144
net.core.wmem_max = 1048576
fs.aio-max-nr = 1048576
net.ipv4.ip_local_port_range = 9000 65500
vm.swappiness=0
vm.max_map_count=524280
vm.min_free_kbytes=512000
vm.nr_hugepages=5389

I'm having an high usage of memory but I was not able to identify the
processes/cache/buffer with high usage



MemTotal:       16330600 kB
MemFree:          936424 kB
Buffers:            3996 kB
Cached:           595708 kB
SwapCached:       835748 kB
Active:          1931588 kB
Inactive:        1204540 kB
Active(anon):    1717000 kB
Inactive(anon):   993436 kB
Active(file):     214588 kB
Inactive(file):   211104 kB
Unevictable:      325580 kB
Mlocked:          325580 kB
SwapTotal:      18870268 kB
SwapFree:       17368004 kB
Dirty:              1696 kB
Writeback:             0 kB
AnonPages:       2855972 kB
Mapped:           221064 kB
Shmem:             93984 kB
Slab:             464292 kB
SReclaimable:      51728 kB
SUnreclaim:       412564 kB
KernelStack:        6600 kB
PageTables:       131396 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:    21517232 kB
Committed_AS:    7045840 kB
VmallocTotal:   34359738367 kB
VmallocUsed:      359380 kB
VmallocChunk:   34359321188 kB
HardwareCorrupted:     0 kB
HugePages_Total:    5389
HugePages_Free:     1086
HugePages_Rsvd:     1076
HugePages_Surp:        0
Hugepagesize:       2048 kB
DirectMap4k:       10240 kB
DirectMap2M:    16766976 kB

I was wondering if could be relate to the hugepage settings.

5389 x 2M =  ~11G on a system with 15G of ram

Is all the space (in my case 11G) reserved at boot time or  it is reserved
based on  the need ?

Regards,
Marco
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