[20210126]探究oracle内存分配3.txt

[20210126]探究oracle内存分配3.txt --//上午做了一番探究,继续测试,我手工增加log_buffer看看如何分配. 1.环境: SYS@book> @ ver1 PORT_STRING                    VERSION        BANNER ------------------------------ -------------- -------------------------------------------------------------------------------- x86_64/Linux 2.4.xx            11.2.0.4.0     Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production SYS@book> show sga Total System Global Area  643084288 bytes Fixed Size                  2255872 bytes Variable Size             205521920 bytes Database Buffers          427819008 bytes Redo Buffers                7487488 bytes SYS@book> create pfile='/tmp/@.ora' from spfile ; File created. --//手工编辑/tmp/book.ora文件,修改log_buffer,仅仅比原来增加1个字节. *.log_buffer=7487489 2.重启数据库: SYS@book> shutdown immediate ; Database closed. Database dismounted. ORACLE instance shut down. SYS@book> startup pfile='/tmp/@.ora' ORACLE instance started. Total System Global Area  647278592 bytes Fixed Size                  2255872 bytes Variable Size             205521920 bytes Database Buffers          427819008 bytes Redo Buffers               11681792 bytes Database mounted. Database opened. --//Redo Buffers =11681792 --// (11681792-7487488)/4/1024/1024 = 1 ,我仅仅增加1个字节,就增级1个GRANULE_SIZE=4m. $ ipcs -m ------ Shared Memory Segments -------- key        shmid      owner      perms      bytes      nattch     status 0x00000000 30605314   oracle    640        16777216   23 0x00000000 30638083   oracle    640        633339904  23 0xe8a8ec10 30670852   oracle    640        2097152    23 $ cat /proc/$(ps -ef | grep smo[n]| awk '{print $2}')/maps | grep SYSV 60000000-61000000 rw-s 00000000 00:0b 30605314                           /SYSV00000000 (deleted) 61000000-86c00000 rw-s 00000000 00:0b 30638083                           /SYSV00000000 (deleted) 86c00000-86e00000 rw-s 00000000 00:0b 30670852                           /SYSVe8a8ec10 (deleted) --//61000000 -60000000 = 16777216 . --//占用4个GRANULE_SIZE. --//Fixed Size+Redo Buffers = 2255872+11681792 = 13937664 --//13937664/4/1024/1024 = 3.322998046875