Red Hat ENTERPRISE LINUX AS 2.1 - Guia de Instalação descarregar pdf (Página 61)

Chapter 16.

Growing the Oracle SGA to 2.7/3.42 GB

in x86 Red Hat Enterprise Linux 3, 4

and 5 Without VLM

16.1. General

Due to 32 bit virtual address limitations workarounds have been implemented in Linux to increase the

maximum size for shared memories. A workaround is to lower the Mapped Base Address for shared

libraries and the SGA Attach Address for shared memory segments. This enables Oracle to attain

an SGA larger than 1.7 GB. To get a better understanding of address mappings in Linux and what

Mapped Base Address is, see Section 15.2, “Linux Memory Layout”.

The following example shows how to increase the size of the SGA without a shared memory file

system. A shared memory file system must be used on x86 to increase SGA beyond 3.42 GB, see

Section 14.8, “Huge Pages and Shared Memory File System in Red Hat Enterprise Linux 3”.

16.2. Mapped Base Address for Shared Libraries in Red Hat

Enterprise Linux 3, 4 and 5

In Red Hat Enterprise Linux 3, 4 or 5 the mapped base for shared libraries does not need to be

lowered since this operation is now done automatically. To verify the mapped base (mapped_base)

for shared libraries execute cat /proc/self/maps in a shell. The directory self in the proc file

system always points to the current running process which in this example is the cat process:

# cat /etc/redhat-release

Red Hat Enterprise Linux AS release 3 (Taroon Update 6)

# cat /proc/self/maps

00a23000-00a38000 r-xp 00000000 08:09 14930 /lib/ld-2.3.2.so

00a38000-00a39000 rw-p 00015000 08:09 14930 /lib/ld-2.3.2.so

00b33000-00c66000 r-xp 00000000 08:09 69576 /lib/tls/libc-2.3.2.so

00c66000-00c69000 rw-p 00132000 08:09 69576 /lib/tls/libc-2.3.2.so

00c69000-00c6c000 rw-p 00000000 00:00 0

00ee5000-00ee6000 r-xp 00000000 08:09 32532 /etc/libcwait.so

00ee6000-00ee7000 rw-p 00000000 08:09 32532 /etc/libcwait.so

08048000-0804c000 r-xp 00000000 08:09 49318 /bin/cat

0804c000-0804d000 rw-p 00003000 08:09 49318 /bin/cat

099db000-099fc000 rw-p 00000000 00:00 0

b73e7000-b75e7000 r--p 00000000 08:02 313698 /usr/lib/locale/locale-archive

b75e7000-b75e8000 rw-p 00000000 00:00 0

bfff8000-c0000000 rw-p ffffc000 00:00 0

# cat /etc/redhat-release

Red Hat Enterprise Linux AS release 4 (Nahant Update 2)

# cat /proc/self/maps

00b68000-00b7d000 r-xp 00000000 03:45 1873128 /lib/ld-2.3.4.so

00b7d000-00b7e000 r--p 00015000 03:45 1873128 /lib/ld-2.3.4.so

00b7e000-00b7f000 rw-p 00016000 03:45 1873128 /lib/ld-2.3.4.so

00b81000-00ca5000 r-xp 00000000 03:45 1938273 /lib/tls/libc-2.3.4.so

00ca5000-00ca6000 r--p 00124000 03:45 1938273 /lib/tls/libc-2.3.4.so

00ca6000-00ca9000 rw-p 00125000 03:45 1938273 /lib/tls/libc-2.3.4.so

00ca9000-00cab000 rw-p 00ca9000 00:00 0

1 2 ... 56 57 58 59 60 61 62 63 64 65 66 ... 159 160

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