[20191223]关于共享内存段相关问题3.txt

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[20191223]关于共享内存段相关问题3.txt --//我一直很好奇如果设置内核参数kernel.shmmax = 68719476736足够大,为什么我的测试实例还是建立3个共享内存段. --//最后1个很特殊key=0xe8a8ec10,大小2M,我看过许多服务器只要key<>=0x00000000,最后都会有1个2M的共享内存段. --//上个星期链接http://blog.itpub.net/267265/viewspace-2669718/=>[20191220]关于共享内存段相关问题.txt --//实际上已经给出答案,我没有写清楚.主要不好表达. --//oracle启动建立的第1个共享内存段主要包括Fixed SGA Size +Redo Buffers. --//oracle启动建立的第2个共享内存段主要包括buffer cache,java pool,large pool,shared pool. --//如何验证log buffer在第1个共享内存段呢? 1.环境: SCOTT@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 2.看看log_buffer在哪里. $ ipcs -m ------ Shared Memory Segments -------- key shmid owner perms bytes nattch status 0x00000000 451674112 oracle 640 12582912 27 0x00000000 451706881 oracle 640 633339904 27 0xe8a8ec10 451739650 oracle 640 2097152 27 $ ipcs -m | awk '{print $5/1024/1024}' | grep -v "^0" 12 604 2 $ 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 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 ..... --//后面一段太长,不贴上来了. $ cat imu.sql $ cat imu.sql SELECT INDX ,FIRST_BUF_KCRFA ,last_buf_kcrfa ,PNEXT_BUF_KCRFA_CLN nxtbufadr ,NEXT_BUF_NUM_KCRFA_CLN nxtbuf# ,BYTES_IN_BUF_KCRFA_CLN "B/buf" ,PVT_STRAND_STATE_KCRFA_CLN state ,STRAND_NUM_ORDINAL_KCRFA_CLN strand# ,PTR_KCRF_PVT_STRAND stradr ,INDEX_KCRF_PVT_STRAND stridx ,SPACE_KCRF_PVT_STRAND strspc ,TXN_KCRF_PVT_STRAND txn ,TOTAL_BUFS_KCRFA totbufs# ,STRAND_SIZE_KCRFA strsz FROM X$KCRFSTRAND ; SYS@book> @ imu INDX FIRST_BUF_KCRFA LAST_BUF_KCRFA NXTBUFADR NXTBUF# B/buf STATE STRAND# STRADR STRIDX STRSPC TXN TOTBUFS# STRSZ ---------- ---------------- ---------------- ---------------- ---------- ---------- ---------- ---------- ---------------- ---------- ---------- ---------- ---------- ---------- 0 0000000060227000 0000000060590E00 000000006050E800 5947 0 0 3735928559 00 0 0 0 6992 3579904 1 0000000060591000 00000000608FAE00 0000000060592C00 13 0 0 3735928559 00 0 0 0 6992 3579904 2 0000000081E27000 00 00 0 0 0 3735928559 0000000081E27054 3735928559 126464 0 249 132096 3 0000000081E49000 00 00 0 0 0 3735928559 0000000081E49054 3735928559 126464 1 249 132096 4 0000000081E6A000 00 00 0 0 0 3735928559 0000000081E6A054 3735928559 126464 2 249 132096 5 0000000081E8B000 00 00 0 0 0 3735928559 0000000081E8B054 3735928559 126464 3 249 132096 6 0000000081EAC000 00 00 0 0 0 3735928559 0000000081EAC054 3735928559 126464 4 249 132096 7 0000000081ECE000 00 00 0 0 0 3735928559 0000000081ECE054 3735928559 126464 5 249 132096 8 0000000081EEF000 00 00 0 0 0 3735928559 00 0 0 0 249 132096 9 0000000081F10000 00 00 0 0 0 3735928559 00 0 0 0 249 132096 10 0000000081F31000 00 00 0 0 0 3735928559 00 0 0 0 249 132096 11 0000000081F53000 00 00 0 0 0 3735928559 00 0 0 0 249 132096 12 0000000081F74000 00 00 0 0 0 3735928559 00 0 0 0 249 132096 13 0000000081F95000 00 00 0 0 0 3735928559 00 0 0 0 249 132096 14 0000000081FB6000 00 00 0 0 0 3735928559 00 0 0 0 249 132096 15 0000000081FD8000 00 00 0 0 0 3735928559 00 0 0 0 249 132096 16 0000000081835000 00 00 0 0 0 3735928559 00 0 0 0 249 132096 17 0000000081856000 00 00 0 0 0 3735928559 00 0 0 0 249 132096 18 0000000081877000 00 00 0 0 0 3735928559 00 0 0 0 249 132096 19 rows selected. SYS@book> show parameter log_buffer NAME TYPE VALUE ---------- -------- --------- log_buffer integer 7159808 SYS@book> @ hide _log_parallelism_max NAME DESCRIPTION DEFAULT_VALUE SESSION_VALUE SYSTEM_VALUE ISSES ISSYS_MOD -------------------- ------------------------------------ ------------- ------------- ------------ ----- --------- _log_parallelism_max Maximum number of log buffer strands TRUE 2 2 FALSE FALSE SYS@book> show parameter cpu_count NAME TYPE VALUE --------- ------- ----- cpu_count integer 24 --//cpu_count=24,这样_log_parallelism_max缺省ceil(cpu_count/16)=2. --//log_buffer/2 = 7159808/2 = 3579904 .与执行@ imu 看到的STRAND_SIZE_KCRFA大小3579904一致.也就是@imu显示的前2行对应log_buffer信息. $ ps -ef | grep lgw[r] oracle 21810 1 0 Dec20 ? 00:00:27 ora_lgwr_book $ cat /proc/21810/smaps | grep -A1 SYSV 60000000-60c00000 rw-s 00000000 00:0b 451674112 /SYSV00000000 (deleted) Size: 12288 kB -- 60c00000-86800000 rw-s 00000000 00:0b 451706881 /SYSV00000000 (deleted) Size: 618496 kB -- 86800000-86a00000 rw-s 00000000 00:0b 451739650 /SYSVe8a8ec10 (deleted) Size: 2048 kB --//注意看第1个共享内存段范围60000000-60c00000,查询@ imu的FIRST_BUF_KCRFA LAST_BUF_KCRFA在这个范围之内.可以证明log_buffer在第1个共享内存段内. --//0x0000000060590E00 - 0x0000000060227000 = 3579392(10进制), 3579392+512 = 3579904.大小等于STRAND_SIZE_KCRFA. --//0x00000000608FAE00 - 0x0000000060591000 = 3579392(10进制). --//512 = 0x200 --//0x0000000060590E00 + 0x200 = 0x0000000060591000,正好等于index=1的FIRST_BUF_KCRFA=0000000060591000. 3.继续测试: SYS@book> oradebug setmypid Statement processed. SYS@book> oradebug DUMPvar SGA kcsgscn_ kcslf kcsgscn_ [06001AE70, 06001AEA0) = 17750548 00000003 00000000 00000000 000422E2 00000000 00000000 00000000 00000000 00000000 6001AB50 00000000 --//可以发现一些重要参数实际都定位在第1个共享内存段内. $ cat fv2.sql column fv_ksmfsnam heading SGAVARNAME for a50 wrap column fv_ksmfstyp heading DATATYPE for a25 wrap column fv_ksmmval_dec heading KSMMVAL_DEC for 99999999999999999999 prompt Display Fixed SGA Variables matching &1 select /*+ ORDERED USE_NL(m) */ f.addr , f.indx , f.ksmfsnam fv_ksmfsnam , to_number(m.ksmmmval, 'XXXXXXXXXXXXXXXX') fv_ksmmval_dec , m.ksmmmval , f.ksmfstyp fv_ksmfstyp , f.ksmfsadr , f.ksmfssiz from x$ksmfsv f, x$ksmmem m where f.ksmfsadr = m.addr and (lower(ksmfsnam) like lower('&1') or lower(ksmfstyp) like lower('&1')) order by ksmfsnam / SYS@book> @ tpt/fv2 kcsgscn_ Display Fixed SGA Variables matching %kcsgscn_% old 14: and (lower(ksmfsnam) like lower('&1') or lower(ksmfstyp) like lower('&1')) new 14: and (lower(ksmfsnam) like lower('%kcsgscn_%') or lower(ksmfstyp) like lower('%kcsgscn_%')) ADDR INDX SGAVARNAME KSMMVAL_DEC KSMMMVAL DATATYPE KSMFSADR KSMFSSIZ ---------------- ---------- -------------------------------------------------- --------------------- ---------------- ------------------------- ---------------- ---------- 0000000009B159E0 3260 kcsgscn_ 13278447743 000000031775087F kcslf 000000006001AE70 48 --//如果查询@ tpt/fv2 %,可以发现KSMFSADR地址都在第1个共享内存段内.

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[20191223]关于共享内存段相关问题3.txt

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