System information

Tips and Techniques: Install and Configure Oracle9i on Red Hat Linux
Advanced Server
VLM_WINDOW_SIZE
This is an undocumented feature and works only with lowering mapped base. This
variable could be set in Oracle user profile file. Increasing VLM_WINDOW_SIZE
has reflected very little performance improvement. It could be set by executing,
export VLM_WINDOW_SIZE=1073741824 (size in bytes, default is 512 MB)
Bigpages
This feature of Advanced Server generates pages of size 4MB Vs the regular 4KB.
And these pages do not get swapped out of memory. The intent is to lock entire
SGA in the memory. Therefore it generates smaller number of page table entries
(pte-s) and results in support of more users. Typically this feature is very useful
with larger SGA size and more number of users. This feature is tuned to perform
with Enterprise kernel.
The number of bigpages used can be displayed by,
cat /proc/meminfo.
To enable bigpages feature, the following steps are to be performed.
1) set one following values in /etc/rc.local.
echo 2 > /proc/sys/kernel/shm-use-bigpages (bigpages in shmfs)
echo 1 > /proc/sys/kernel/shm-use-bigpages (bigpages in SYSV memory)
echo 0 > /proc/sys/kernel/shm-use-bigpages (disable bigpages feature, default)
Use bigpages either in shmfs or SYSV. To disable bigpages use last entry.
2) The following line is added to /etc/lilo.conf in the boot section and LILO is
reconfigured and system is rebooted.
append = "bigpages=xxxxMB"
Where xxxx is value of big pages in MB.
The suggested values for bigpages / SGA combinations on a 8GB machine are
listed.
For a SGA of 4GB, bigpages of size 4100MB could be set and for SGA of 2GB,
bigpages of size 2100MB could be set.
The Maximum size of 5.4 GB of SGA can be created on 8 GB machine.
Sockets and Processes
Sockets : Defines the local port range that is used by TCP and UDP to choose the
local port. The first number is the first, the second the last local port number.)
echo 1024 65000 > /proc/sys/net/ipv4/ip_local_port_range
Tips and Techniques: Install and Configure Oracle9i on Red Hat Linux Advanced Server Page 14