[20191220]關於共享記憶體段相關問題.txt

lfree發表於2019-12-20

[20191220]關於共享記憶體段相關問題.txt

--//我一直很好奇如果設定核心引數kernel.shmmax = 68719476736足夠大,為什麼我的測試例項還是建立3個共享記憶體段.
--//最後1個很特殊key=0xe8a8ec10,大小2M,我看過許多伺服器只要key<>=0x00000000,最後都會有1個2M的共享記憶體段.
--//oracle為什麼不是建立1個共享記憶體段呢?簡單探究看看.

1.測試環境:
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 parameter sga_max_size
NAME         TYPE        VALUE
------------ ----------- -----
sga_max_size big integer 620M
--//Granule Size=4194304

$ ipcs -m
------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status
0x00000000 423034880  oracle    640        12582912   20
0x00000000 423067649  oracle    640        633339904  20
0xe8a8ec10 423100418  oracle    640        2097152    20

$ ipcs -m | awk '{print $5/1024/1024}' | grep -v "^0"
12
604
2

2.一些引數設定:
SYS@book> show parameter db_cache_size
NAME          TYPE        VALUE
------------- ----------- ------
db_cache_size big integer 408M

SYS@book> show parameter shared_pool_size
NAME             TYPE        VALUE
---------------- ----------- ------
shared_pool_size big integer 172M

SYS@book> show parameter java_pool_size
NAME           TYPE        VALUE
-------------- ----------- -----
java_pool_size big integer 12M

SYS@book> show parameter large_pool_size
NAME            TYPE        VALUE
--------------- ----------- ------
large_pool_size big integer 12M

SYS@book> show parameter sga_max_size
NAME         TYPE        VALUE
------------ ----------- -----
sga_max_size big integer 616M

--//注:我的測試環境一直採用手動管理.設定db_cache_size=408,shared_pool_size=172M,java_pool_size=12M,large_pool_size=12M,sga_max_size=616M.
--//剩下616-172-408-12-12= 12M.這12M正好和前面ipcs -m看到的第一共享記憶體段相對應.

3.測試與驗證:
$ cat memalloc.sql
col component format a32
select min(BASEADDR), max(BASEADDR), count(1) Granules, sum(a.gransize)/1048576 MB, a.GRANFLAGS, component, a.GRANSTATE
from x$ksmge a, x$kmgsct b
where a.grantype = b.grantype (+)
group by a.GRANFLAGS, component, a.GRANSTATE
order by 1,2;

pause press enter .....

select a.BASEADDR, a.gransize, a.GRANFLAGS, b.component, a.GRANSTATE
from x$ksmge a, x$kmgsct b
where a.grantype = b.grantype (+)
order by 1,2;

SYS@book> @ memalloc
MIN(BASEADDR)    MAX(BASEADDR)      GRANULES         MB  GRANFLAGS COMPONENT            GRANSTATE
---------------- ---------------- ---------- ---------- ---------- -------------------- ----------------
0000000060C00000 000000007A000000        102        408          4 DEFAULT buffer cache ALLOC
000000007A400000 000000007AC00000          3         12          4 java pool            ALLOC
000000007B000000 000000007B800000          3         12          4 large pool           ALLOC
000000007BC00000 0000000086400000         43        172          4 shared pool          ALLOC
press enter .....

BASEADDR           GRANSIZE  GRANFLAGS COMPONENT                        GRANSTATE
---------------- ---------- ---------- -------------------------------- ----------------
0000000060C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000061000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000061400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000061800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000061C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000062000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000062400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000062800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000062C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000063000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000063400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000063800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000063C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000064000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000064400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000064800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000064C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000065000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000065400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000065800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000065C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000066000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000066400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000066800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000066C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000067000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000067400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000067800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000067C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000068000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000068400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000068800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000068C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000069000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000069400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000069800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000069C00000    4194304          4 DEFAULT buffer cache             ALLOC
000000006A000000    4194304          4 DEFAULT buffer cache             ALLOC
000000006A400000    4194304          4 DEFAULT buffer cache             ALLOC
000000006A800000    4194304          4 DEFAULT buffer cache             ALLOC
000000006AC00000    4194304          4 DEFAULT buffer cache             ALLOC
000000006B000000    4194304          4 DEFAULT buffer cache             ALLOC
000000006B400000    4194304          4 DEFAULT buffer cache             ALLOC
000000006B800000    4194304          4 DEFAULT buffer cache             ALLOC
000000006BC00000    4194304          4 DEFAULT buffer cache             ALLOC
000000006C000000    4194304          4 DEFAULT buffer cache             ALLOC
000000006C400000    4194304          4 DEFAULT buffer cache             ALLOC
000000006C800000    4194304          4 DEFAULT buffer cache             ALLOC
000000006CC00000    4194304          4 DEFAULT buffer cache             ALLOC
000000006D000000    4194304          4 DEFAULT buffer cache             ALLOC
000000006D400000    4194304          4 DEFAULT buffer cache             ALLOC
000000006D800000    4194304          4 DEFAULT buffer cache             ALLOC
000000006DC00000    4194304          4 DEFAULT buffer cache             ALLOC
000000006E000000    4194304          4 DEFAULT buffer cache             ALLOC
000000006E400000    4194304          4 DEFAULT buffer cache             ALLOC
000000006E800000    4194304          4 DEFAULT buffer cache             ALLOC
000000006EC00000    4194304          4 DEFAULT buffer cache             ALLOC
000000006F000000    4194304          4 DEFAULT buffer cache             ALLOC
000000006F400000    4194304          4 DEFAULT buffer cache             ALLOC
000000006F800000    4194304          4 DEFAULT buffer cache             ALLOC
000000006FC00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000070000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000070400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000070800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000070C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000071000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000071400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000071800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000071C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000072000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000072400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000072800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000072C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000073000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000073400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000073800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000073C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000074000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000074400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000074800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000074C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000075000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000075400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000075800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000075C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000076000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000076400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000076800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000076C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000077000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000077400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000077800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000077C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000078000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000078400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000078800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000078C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000079000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000079400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000079800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000079C00000    4194304          4 DEFAULT buffer cache             ALLOC
000000007A000000    4194304          4 DEFAULT buffer cache             ALLOC
000000007A400000    4194304          4 java pool                        ALLOC
000000007A800000    4194304          4 java pool                        ALLOC
000000007AC00000    4194304          4 java pool                        ALLOC
000000007B000000    4194304          4 large pool                       ALLOC
000000007B400000    4194304          4 large pool                       ALLOC
000000007B800000    4194304          4 large pool                       ALLOC
000000007BC00000    4194304          4 shared pool                      ALLOC
000000007C000000    4194304          4 shared pool                      ALLOC
000000007C400000    4194304          4 shared pool                      ALLOC
000000007C800000    4194304          4 shared pool                      ALLOC
000000007CC00000    4194304          4 shared pool                      ALLOC
000000007D000000    4194304          4 shared pool                      ALLOC
000000007D400000    4194304          4 shared pool                      ALLOC
000000007D800000    4194304          4 shared pool                      ALLOC
000000007DC00000    4194304          4 shared pool                      ALLOC
000000007E000000    4194304          4 shared pool                      ALLOC
000000007E400000    4194304          4 shared pool                      ALLOC
000000007E800000    4194304          4 shared pool                      ALLOC
000000007EC00000    4194304          4 shared pool                      ALLOC
000000007F000000    4194304          4 shared pool                      ALLOC
000000007F400000    4194304          4 shared pool                      ALLOC
000000007F800000    4194304          4 shared pool                      ALLOC
000000007FC00000    4194304          4 shared pool                      ALLOC
0000000080000000    4194304          4 shared pool                      ALLOC
0000000080400000    4194304          4 shared pool                      ALLOC
0000000080800000    4194304          4 shared pool                      ALLOC
0000000080C00000    4194304          4 shared pool                      ALLOC
0000000081000000    4194304          4 shared pool                      ALLOC
0000000081400000    4194304          4 shared pool                      ALLOC
0000000081800000    4194304          4 shared pool                      ALLOC
0000000081C00000    4194304          4 shared pool                      ALLOC
0000000082000000    4194304          4 shared pool                      ALLOC
0000000082400000    4194304          4 shared pool                      ALLOC
0000000082800000    4194304          4 shared pool                      ALLOC
0000000082C00000    4194304          4 shared pool                      ALLOC
0000000083000000    4194304          4 shared pool                      ALLOC
0000000083400000    4194304          4 shared pool                      ALLOC
0000000083800000    4194304          4 shared pool                      ALLOC
0000000083C00000    4194304          4 shared pool                      ALLOC
0000000084000000    4194304          4 shared pool                      ALLOC
0000000084400000    4194304          4 shared pool                      ALLOC
0000000084800000    4194304          4 shared pool                      ALLOC
0000000084C00000    4194304          4 shared pool                      ALLOC
0000000085000000    4194304          4 shared pool                      ALLOC
0000000085400000    4194304          4 shared pool                      ALLOC
0000000085800000    4194304          4 shared pool                      ALLOC
0000000085C00000    4194304          4 shared pool                      ALLOC
0000000086000000    4194304          4 shared pool                      ALLOC
0000000086400000    4194304          4 shared pool                      ALLOC
151 rows selected.

--//測試環境都是手動管理,記憶體分配都是連續的.
--//如果你仔細看MIN(BASEADDR),MAX(BASEADDR)可以發現是首尾相連的.
--//4*1024*1024 = 4194304 = = 0x400000
--//MAX(BASEADDR)+0x400000正好等於下一行的MIN(BASEADDR).

$ ps -ef | grep lgw[r]
oracle   19717     1  0 09:25 ?        00:00:02 ora_lgwr_book

$ cat /proc/19717/smaps  | grep -A1 SYSV
60000000-60c00000 rw-s 00000000 00:0b 451543040                          /SYSV00000000 (deleted)
Size:              12288 kB
--
60c00000-86800000 rw-s 00000000 00:0b 451575809                          /SYSV00000000 (deleted)
Size:             618496 kB
--
86800000-86a00000 rw-s 00000000 00:0b 451608578                          /SYSVe8a8ec10 (deleted)
Size:               2048 kB
--//這些資訊也可以對上.
--//還可以看出執行@ memalloc看到的內容就是ipcs -m的第2個共享記憶體段.

--//查詢v$sgainfo
SYS@book> select * from v$sgainfo ;
NAME                                          BYTES RES
---------------------------------------- ---------- ---
Fixed SGA Size                              2255872 No
Redo Buffers                                7487488 No
Buffer Cache Size                         427819008 Yes
Shared Pool Size                          180355072 Yes
Large Pool Size                            12582912 Yes
Java Pool Size                             12582912 Yes
Streams Pool Size                                 0 Yes
Shared IO Pool Size                               0 Yes
Granule Size                                4194304 No
Maximum SGA Size                          643084288 No
Startup overhead in Shared Pool           133446832 No
Free SGA Memory Available                         0
12 rows selected.

--//Fixed SGA Size+Redo Buffers = 2255872+7487488 = 9743360, 9743360/1024/1024 = 9.29M.
--//從檢視v$sgainfo可以看出Fixed SGA Size,Redo Buffers一定在ipcs -m輸出的第1個共享記憶體段內.
--//你可以嘗試修改log_buffer大小,變化一定在ipcs -m輸出的第1個共享記憶體段內.我不貼上來了.
--//而Fixed SGA Size與引數processes存在密切關係.

4.繼續測試:
--//連結:http://blog.itpub.net/267265/viewspace-2667945/=>[20191211]11g streams_pool_size引數.txt
$ expdp scott/book
...

--//再看oracle記憶體分配情況:
SYS@book> @ memalloc
MIN(BASEADDR)    MAX(BASEADDR)      GRANULES         MB  GRANFLAGS COMPONENT                        GRANSTATE
---------------- ---------------- ---------- ---------- ---------- -------------------------------- ----------------
0000000060C00000 0000000061C00000          5         20          4 streams pool                     ALLOC
0000000062000000 0000000086400000         48        192          4 shared pool                      ALLOC
0000000063400000 000000007A000000         92        368          4 DEFAULT buffer cache             ALLOC
000000007A400000 000000007AC00000          3         12          4 java pool                        ALLOC
000000007B000000 000000007B800000          3         12          4 large pool                       ALLOC
press enter .....

BASEADDR           GRANSIZE  GRANFLAGS COMPONENT                        GRANSTATE
---------------- ---------- ---------- -------------------------------- ----------------
0000000060C00000    4194304          4 streams pool                     ALLOC
0000000061000000    4194304          4 streams pool                     ALLOC
0000000061400000    4194304          4 streams pool                     ALLOC
0000000061800000    4194304          4 streams pool                     ALLOC
0000000061C00000    4194304          4 streams pool                     ALLOC
0000000062000000    4194304          4 shared pool                      ALLOC
0000000062400000    4194304          4 shared pool                      ALLOC
0000000062800000    4194304          4 shared pool                      ALLOC
0000000062C00000    4194304          4 shared pool                      ALLOC
0000000063000000    4194304          4 shared pool                      ALLOC
0000000063400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000063800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000063C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000064000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000064400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000064800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000064C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000065000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000065400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000065800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000065C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000066000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000066400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000066800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000066C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000067000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000067400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000067800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000067C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000068000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000068400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000068800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000068C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000069000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000069400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000069800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000069C00000    4194304          4 DEFAULT buffer cache             ALLOC
000000006A000000    4194304          4 DEFAULT buffer cache             ALLOC
000000006A400000    4194304          4 DEFAULT buffer cache             ALLOC
000000006A800000    4194304          4 DEFAULT buffer cache             ALLOC
000000006AC00000    4194304          4 DEFAULT buffer cache             ALLOC
000000006B000000    4194304          4 DEFAULT buffer cache             ALLOC
000000006B400000    4194304          4 DEFAULT buffer cache             ALLOC
000000006B800000    4194304          4 DEFAULT buffer cache             ALLOC
000000006BC00000    4194304          4 DEFAULT buffer cache             ALLOC
000000006C000000    4194304          4 DEFAULT buffer cache             ALLOC
000000006C400000    4194304          4 DEFAULT buffer cache             ALLOC
000000006C800000    4194304          4 DEFAULT buffer cache             ALLOC
000000006CC00000    4194304          4 DEFAULT buffer cache             ALLOC
000000006D000000    4194304          4 DEFAULT buffer cache             ALLOC
000000006D400000    4194304          4 DEFAULT buffer cache             ALLOC
000000006D800000    4194304          4 DEFAULT buffer cache             ALLOC
000000006DC00000    4194304          4 DEFAULT buffer cache             ALLOC
000000006E000000    4194304          4 DEFAULT buffer cache             ALLOC
000000006E400000    4194304          4 DEFAULT buffer cache             ALLOC
000000006E800000    4194304          4 DEFAULT buffer cache             ALLOC
000000006EC00000    4194304          4 DEFAULT buffer cache             ALLOC
000000006F000000    4194304          4 DEFAULT buffer cache             ALLOC
000000006F400000    4194304          4 DEFAULT buffer cache             ALLOC
000000006F800000    4194304          4 DEFAULT buffer cache             ALLOC
000000006FC00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000070000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000070400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000070800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000070C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000071000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000071400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000071800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000071C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000072000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000072400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000072800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000072C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000073000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000073400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000073800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000073C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000074000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000074400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000074800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000074C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000075000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000075400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000075800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000075C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000076000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000076400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000076800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000076C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000077000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000077400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000077800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000077C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000078000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000078400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000078800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000078C00000    4194304          4 DEFAULT buffer cache             ALLOC
0000000079000000    4194304          4 DEFAULT buffer cache             ALLOC
0000000079400000    4194304          4 DEFAULT buffer cache             ALLOC
0000000079800000    4194304          4 DEFAULT buffer cache             ALLOC
0000000079C00000    4194304          4 DEFAULT buffer cache             ALLOC
000000007A000000    4194304          4 DEFAULT buffer cache             ALLOC
000000007A400000    4194304          4 java pool                        ALLOC
000000007A800000    4194304          4 java pool                        ALLOC
000000007AC00000    4194304          4 java pool                        ALLOC
000000007B000000    4194304          4 large pool                       ALLOC
000000007B400000    4194304          4 large pool                       ALLOC
000000007B800000    4194304          4 large pool                       ALLOC
000000007BC00000    4194304          4 shared pool                      ALLOC
000000007C000000    4194304          4 shared pool                      ALLOC
000000007C400000    4194304          4 shared pool                      ALLOC
000000007C800000    4194304          4 shared pool                      ALLOC
000000007CC00000    4194304          4 shared pool                      ALLOC
000000007D000000    4194304          4 shared pool                      ALLOC
000000007D400000    4194304          4 shared pool                      ALLOC
000000007D800000    4194304          4 shared pool                      ALLOC
000000007DC00000    4194304          4 shared pool                      ALLOC
000000007E000000    4194304          4 shared pool                      ALLOC
000000007E400000    4194304          4 shared pool                      ALLOC
000000007E800000    4194304          4 shared pool                      ALLOC
000000007EC00000    4194304          4 shared pool                      ALLOC
000000007F000000    4194304          4 shared pool                      ALLOC
000000007F400000    4194304          4 shared pool                      ALLOC
000000007F800000    4194304          4 shared pool                      ALLOC
000000007FC00000    4194304          4 shared pool                      ALLOC
0000000080000000    4194304          4 shared pool                      ALLOC
0000000080400000    4194304          4 shared pool                      ALLOC
0000000080800000    4194304          4 shared pool                      ALLOC
0000000080C00000    4194304          4 shared pool                      ALLOC
0000000081000000    4194304          4 shared pool                      ALLOC
0000000081400000    4194304          4 shared pool                      ALLOC
0000000081800000    4194304          4 shared pool                      ALLOC
0000000081C00000    4194304          4 shared pool                      ALLOC
0000000082000000    4194304          4 shared pool                      ALLOC
0000000082400000    4194304          4 shared pool                      ALLOC
0000000082800000    4194304          4 shared pool                      ALLOC
0000000082C00000    4194304          4 shared pool                      ALLOC
0000000083000000    4194304          4 shared pool                      ALLOC
0000000083400000    4194304          4 shared pool                      ALLOC
0000000083800000    4194304          4 shared pool                      ALLOC
0000000083C00000    4194304          4 shared pool                      ALLOC
0000000084000000    4194304          4 shared pool                      ALLOC
0000000084400000    4194304          4 shared pool                      ALLOC
0000000084800000    4194304          4 shared pool                      ALLOC
0000000084C00000    4194304          4 shared pool                      ALLOC
0000000085000000    4194304          4 shared pool                      ALLOC
0000000085400000    4194304          4 shared pool                      ALLOC
0000000085800000    4194304          4 shared pool                      ALLOC
0000000085C00000    4194304          4 shared pool                      ALLOC
0000000086000000    4194304          4 shared pool                      ALLOC
0000000086400000    4194304          4 shared pool                      ALLOC
151 rows selected.
--//注:這裡看shared pool被分成2部分.
--//DEFAULT buffer cache=408-368 = 40M.前面40M被分給streams pool=20M,shared poo=20M.

SYS@book> select * from v$sgainfo ;
NAME                                          BYTES RES
---------------------------------------- ---------- ---
Fixed SGA Size                              2255872 No
Redo Buffers                                7487488 No
Buffer Cache Size                         385875968 Yes
Shared Pool Size                          201326592 Yes
Large Pool Size                            12582912 Yes
Java Pool Size                             12582912 Yes
Streams Pool Size                          20971520 Yes
Shared IO Pool Size                               0 Yes
Granule Size                                4194304 No
Maximum SGA Size                          643084288 No
Startup overhead in Shared Pool           133446832 No
Free SGA Memory Available                         0
12 rows selected.
--//注:與我連結測試不同http://blog.itpub.net/267265/viewspace-2667945/,我當時Shared Pool Size沒有變化.

5.總結:
--//也就是從以上測試可以看出,oracle啟動建立的第1個共享記憶體段主要包括Fixed SGA Size +Redo Buffers.可以大概猜測
--//oracle啟動為什麼會出現這樣的情況.

來自 “ ITPUB部落格 ” ,連結:http://blog.itpub.net/267265/viewspace-2669718/,如需轉載,請註明出處,否則將追究法律責任。

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