[20181109]12cR2 的pre_page_sga参数
[20181109]12cr2 的pre_page_sga参数.txt
--//12cr2改变了参数pre_page_sga设置为true.设置为true有好处也有缺点.
--//先看看官方的定义:
http://docs.oracle.com/cd/e11882_01/server.112/e40402/initparams201.htm#refrn10174
pre_page_sga determines whether oracle reads the entire sga into memory at instance startup. operating system page table
entries are then prebuilt for each page of the sga. this setting can increase the amount of time necessary for instance
startup, but it is likely to decrease the amount of time necessary for oracle to reach its full performance capacity
after startup.
note:
this setting does not prevent your operating system from paging or swapping the sga after it is initially read into
memory.
pre_page_sga can increase the process startup duration, because every process that starts must access every page in the
sga. the cost of this strategy is fixed; however, you might simply determine that 20,000 pages must be touched every
time a process starts. this approach can be useful with some applications, but not with all applications. overhead can
be significant if your system frequently creates and destroys processes by, for example, continually logging on and
logging off.
the advantage that pre_page_sga can afford depends on page size. for example, if the sga is 80 mb in size and the page
size is 4 kb, then 20,000 pages must be touched to refresh the sga (80,000/4 = 20,000).
if the system permits you to set a 4 mb page size, then only 20 pages must be touched to refresh the sga (80,000/4,000 =
20). the page size is operating system-specific and generally cannot be changed. some operating systems, however, have a
special implementation for shared memory whereby you can change the page size.
--//可以发现使用pre_page_sga=true,仅仅在启动是读整个sga进入内存,如果你设置很大,现在的服务器内存上几百g很正常,启动就慢很多,
--//但是能很快达到最佳性能.但是它并不能避免交换使用.
--//如果你仔细读后面的信息,可以发现pre_page_sga=true的情况设置使用hugepages非常必要.
--//这也是我为什么强调安装oracle必须配置hugepags作为必要的步骤,现在许多安装人员基本不做,而业务开展以后要改也带来不必要的
--//麻烦,毕竟要停业务.
1.环境:
sql> select banner_full from v$version;
banner_full
--------------------------------------------------------------------------------
oracle database 18c enterprise edition release 18.0.0.0.0 - production
version 18.3.0.0.0
--//办公环境没有12c,那18c来说明问题一样的.
sql> show pdbs
con_id con_name open mode restricted
------ -------- ---------- ----------
2 pdb$seed read only no
3 orcl read write no
sql> show parameter pre_page_sga
name type value
------------- ----------- ------------------------------
pre_page_sga boolean true
sql> show spparameter pre_page_sga
sid name type value
-------- ----------------------------- ----------- ----------------------------
* pre_page_sga boolean
--//参数pre_page_sga没有写入spfile参数文件,12cr2以上缺省设置为true.oracle 之所以这样设置主要考虑pdb的原因(我个人人为)
2.看看内存使用情况:
# cat /proc/meminfo | grep -i page
anonpages: 2973340 kb
pagetables: 803364 kb
anonhugepages: 0 kb
hugepages_total: 0
hugepages_free: 0
hugepages_rsvd: 0
hugepages_surp: 0
hugepagesize: 2048 kb
--//页面表消耗800m.
# ps -ef | grep orclcd[b]|wc
85 684 5753
--//仅仅85个进程.
# top -u oracle
--//按f,移动到res列,选择s,改变排序模式.这样按照res排序.
top - 08:58:20 up 70 days, 5:06, 3 users, load average: 1.02, 1.04, 1.05
tasks: 541 total, 1 running, 540 sleeping, 0 stopped, 0 zombie
%cpu(s): 0.2 us, 0.1 sy, 0.0 ni, 99.7 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
kib mem : 65709508 total, 8128052 free, 6214192 used, 51367264 buff/cache
kib swap: 16773116 total, 16773116 free, 0 used. 30169176 avail mem
pid user pr ni virt res shr s %cpu %mem time+ command
12970 oracle 20 0 29.2g 11.3g 11.2g s 0.0 18.0 12:10.07 ora_dbw0_orclcd
14369 oracle 20 0 29.2g 3.2g 3.1g s 0.0 5.1 3:24.60 ora_w00b_orclcd
13094 oracle 20 0 29.3g 3.0g 2.9g s 0.0 4.7 4:29.54 ora_w003_orclcd
14420 oracle 20 0 29.2g 2.6g 2.5g s 0.0 4.1 4:17.85 ora_w00f_orclcd
13065 oracle 20 0 29.2g 2.2g 2.2g s 0.0 3.6 20:24.95 ora_p002_orclcd
13067 oracle 20 0 29.2g 2.2g 2.1g s 0.0 3.5 21:26.00 ora_p003_orclcd
14333 oracle 20 0 29.2g 2.1g 2.0g s 0.0 3.3 2:26.60 ora_w005_orclcd
14342 oracle 20 0 29.2g 2.1g 2.0g s 0.0 3.3 2:27.30 ora_w007_orclcd
14365 oracle 20 0 29.2g 2.0g 1.9g s 0.0 3.2 2:28.03 ora_w00a_orclcd
14415 oracle 20 0 29.2g 1.9g 1.8g s 0.0 3.0 2:12.27 ora_w00e_orclcd
12986 oracle 20 0 29.2g 1.9g 1.8g s 0.0 3.0 2:56.72 ora_w000_orclcd
13308 oracle 20 0 29.2g 1.8g 1.8g s 0.0 2.9 110:41.60 ora_cjq0_orclcd
13061 oracle 20 0 29.2g 1.8g 1.7g s 0.0 2.8 24:00.66 ora_p000_orclcd
14360 oracle 20 0 29.2g 1.8g 1.7g s 0.0 2.8 2:16.13 ora_w009_orclcd
13063 oracle 20 0 29.3g 1.7g 1.6g s 0.0 2.7 23:02.60 ora_p001_orclcd
14410 oracle 20 0 29.2g 1.6g 1.5g s 0.0 2.5 1:45.68 ora_w00d_orclcd
14337 oracle 20 0 29.2g 1.6g 1.5g s 0.0 2.5 2:59.62 ora_w006_orclcd
12948 oracle 20 0 29.1g 1.5g 1.5g s 0.0 2.4 1:33.42 ora_mman_orclcd
13051 oracle 20 0 29.2g 1.4g 1.4g s 0.0 2.2 30:11.14 ora_imco_orclcd
14403 oracle 20 0 29.2g 1.3g 1.2g s 0.0 2.0 2:07.15 ora_w00c_orclcd
13000 oracle 20 0 29.2g 1.2g 1.2g s 0.0 2.0 25:06.94 ora_mmon_orclcd
13073 oracle 20 0 29.2g 1.1g 1.0g s 0.0 1.7 5:34.12 ora_p006_orclcd
13075 oracle 20 0 29.1g 1.1g 1.0g s 0.0 1.7 5:35.03 ora_p007_orclcd
13099 oracle 20 0 29.2g 1.0g 1.0g s 0.0 1.6 1:24.58 ora_w004_orclcd
...
--//你可以发现一些oracle相关进程res占用很大的内存.
--//贴一个我们生产系统(exadata的情况): pre_page_sga=false.
# cat /proc/meminfo | grep -i page
anonpages: 22546648 kb
pagetables: 1593420 kb
hugepages_total: 78600
hugepages_free: 3961
hugepages_rsvd: 3954
hugepages_surp: 0
hugepagesize: 2048 kb
--//页面表仅仅消耗1.6g.
# ps -ef | grep -i oracled[b]|wc
3648 32832 266538
--//3648个进程.
top - 09:04:59 up 1429 days, 6:40, 1 user, load average: 4.18, 3.99, 3.64
tasks: 3963 total, 4 running, 3959 sleeping, 0 stopped, 0 zombie
cpu(s): 20.7%us, 5.6%sy, 0.0%ni, 73.1%id, 0.0%wa, 0.0%hi, 0.6%si, 0.0%st
mem: 264235388k total, 244039764k used, 20195624k free, 9676076k buffers
swap: 25165820k total, 0k used, 25165820k free, 33019892k cached
pid ppid user pr ni virt res shr s %cpu %mem time+ ruser uid group tty p swap time code data nflt ndrt wchan flags command
112340 12166 oracle 20 0 951m 499m 12m s 0.0 0.2 1348:50 oracle 1001 oinstall ? 20 451m 22,28 36 857m 0 0 futex_wai ..4.2... /u01/app/oracle/product/agent12c/core/12.1.0.4.0/jdk/bin/java -xmx223m -xx:maxperm
25209 1 oracle 20 0 76.1g 121m 21m s 0.0 0.0 39:38.45 oracle 1001 asmadmin ? 23 76g 39:38 185m 6076 0 0 semtimedo ..4.2... ora_arc9_dbcn1
24016 1 oracle 20 0 76.1g 112m 17m s 0.9 0.0 28805:22 oracle 1001 asmadmin ? 3 75g 480,05 185m 3564 4 0 poll_sche ..4.2... ora_dia0_dbcn1
25199 1 oracle 20 0 76.1g 110m 21m s 0.0 0.0 39:52.84 oracle 1001 asmadmin ? 23 76g 39:52 185m 6168 0 0 semtimedo ..4.2... ora_arc4_dbcn1
25203 1 oracle 20 0 76.1g 110m 21m s 0.0 0.0 39:15.27 oracle 1001 asmadmin ? 23 76g 39:15 185m 6140 0 0 semtimedo ..4.2... ora_arc6_dbcn1
25201 1 oracle 20 0 76.1g 110m 21m s 0.0 0.0 78:29.38 oracle 1001 asmadmin ? 12 76g 78:29 185m 5372 0 0 semtimedo ..4.2... ora_arc5_dbcn1
25205 1 oracle 20 0 76.1g 109m 21m s 0.0 0.0 40:12.35 oracle 1001 asmadmin ? 9 76g 40:12 185m 6152 0 0 semtimedo ..4.2... ora_arc7_dbcn1
25207 1 oracle 20 0 76.1g 109m 21m s 0.0 0.0 40:05.73 oracle 1001 asmadmin ? 20 76g 40:05 185m 6120 0 0 semtimedo ..4.2... ora_arc8_dbcn1
25197 1 oracle 20 0 76.1g 109m 21m s 0.0 0.0 40:26.04 oracle 1001 asmadmin ? 23 76g 40:26 185m 6120 0 0 semtimedo ..4.2... ora_arc3_dbcn1
25191 1 oracle 20 0 76.1g 108m 21m s 0.0 0.0 38:48.21 oracle 1001 asmadmin ? 3 76g 38:48 185m 6096 8 0 semtimedo ..4.2... ora_arc0_dbcn1
25193 1 oracle 20 0 76.1g 108m 21m s 0.0 0.0 39:19.44 oracle 1001 asmadmin ? 6 76g 39:19 185m 6068 0 0 semtimedo ..4.2... ora_arc1_dbcn1
28227 1 oracle 20 0 76.1g 107m 20m s 0.0 0.0 27:07.26 oracle 1001 asmadmin ? 19 76g 27:07 185m 5112 0 0 semtimedo ..4.2... ora_arc7_dben1
28225 1 oracle 20 0 76.1g 105m 20m s 0.0 0.0 27:03.77 oracle 1001 asmadmin ? 5 75g 27:03 185m 4988 0 0 semtimedo ..4.2... ora_arc6_dben1
28213 1 oracle 20 0 76.1g 104m 20m s 0.0 0.0 27:05.39 oracle 1001 asmadmin ? 9 76g 27:05 185m 4984 0 0 semtimedo ..4.2... ora_arc0_dben1
28229 1 oracle 20 0 76.1g 100m 21m s 0.0 0.0 27:14.12 oracle 1001 asmadmin ? 17 76g 27:14 185m 4992 0 0 semtimedo ..4.2... ora_arc8_dben1
28221 1 oracle 20 0 76.1g 98m 21m s 0.0 0.0 27:20.46 oracle 1001 asmadmin ? 3 76g 27:20 185m 5060 0 0 semtimedo ..4.2... ora_arc4_dben1
28231 1 oracle 20 0 76.1g 96m 20m s 0.0 0.0 27:05.01 oracle 1001 asmadmin ? 9 76g 27:05 185m 4992 0 0 semtimedo ..4.2... ora_arc9_dben1
28223 1 oracle 20 0 76.1g 94m 21m s 0.0 0.0 27:03.38 oracle 1001 asmadmin ? 19 76g 27:03 185m 4960 0 0 semtimedo ..4.2... ora_arc5_dben1
80614 1 oracle 20 0 76.1g 93m 20m s 0.0 0.0 9:43.50 oracle 1001 asmadmin ? 5 76g 9:43 185m 4988 0 0 semtimedo ..4.2... ora_arc2_dben1
27568 1 oracle -2 0 76.1g 88m 17m s 0.6 0.0 3825:00 oracle 1001 asmadmin ? 18 75g 63,45 185m 3732 0 0 poll_sche ..4.2... ora_lms1_dben1
27564 1 oracle -2 0 76.1g 88m 17m s 0.6 0.0 3781:02 oracle 1001 asmadmin ? 0 75g 63,01 185m 3732 0 0 poll_sche ..4.2... ora_lms0_dben1
24037 1 oracle 20 0 76.1g 86m 19m s 0.0 0.0 1252:39 oracle 1001 asmadmin ? 22 75g 20,52 185m 52m 0 0 semtimedo ..4.2... ora_dbw0_dbcn1
25171 1 oracle 20 0 76.0g 85m 27m s 0.0 0.0 2295:56 oracle 1001 asmadmin ? 1 75g 38,15 185m 4644 1 0 semtimedo ..4.2... ora_rsm0_dbcn1
24041 1 oracle 20 0 76.1g 85m 18m s 0.0 0.0 1157:28 oracle 1001 asmadmin ? 22 75g 19,17 185m 52m 0 0 semtimedo ..4.2... ora_dbw2_dbcn1
24039 1 oracle 20 0 76.1g 83m 18m s 0.0 0.0 1173:16 oracle 1001 asmadmin ? 0 75g 19,33 185m 51m 0 0 semtimedo ..4.2... ora_dbw1_dbcn1
28215 1 oracle 20 0 76.1g 83m 19m s 0.0 0.0 70:07.81 oracle 1001 asmadmin ? 23 75g 70:07 185m 4172 0 0 semtimedo ..4.2... ora_arc1_dben1
27557 1 oracle 20 0 76.0g 80m 17m s 2.8 0.0 23005:17 oracle 1001 asmadmin ? 3 75g 383,25 185m 3564 0 0 poll_sche ..4.2... ora_dia0_dben1
--//不知道为什么这个版本的swap显示这么大.实际上应该是0.
3.难道11g下有bug还是一些问题.我在测试重新测试看看.我以前看到不是这样的情况:
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> create pfile='/tmp/@.ora' from spfile;
file created.
--//修改/tmp/book.ora文件,修改加入如下:
*.use_large_pages=false
*.pre_page_sga=true
sys@book> startup pfile='/tmp/book.ora;
oracle instance started.
total system global area 643084288 bytes
fixed size 2255872 bytes
variable size 205521920 bytes
database buffers 427819008 bytes
redo buffers 7487488 bytes
database mounted.
database opened.
--//忘记输入结尾的引号,竟然也能通过.
sys@book> show parameter pre_page_sga
name type value
------------ ------- -------
pre_page_sga boolean true
$ cat /proc/meminfo | grep hugepages
anonhugepages: 0 kb
hugepages_total: 104
hugepages_free: 104
hugepages_rsvd: 0
hugepages_surp: 0
--//可以发现hugepages_total=hugepages_free.表明没有使用hugepages.
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
# top -u oracle
--//按照res排序.
top - 09:22:00 up 1065 days, 45 min, 1 user, load average: 0.18, 0.14, 0.10
tasks: 245 total, 1 running, 244 sleeping, 0 stopped, 0 zombie
cpu(s): 0.0%us, 0.1%sy, 0.0%ni, 99.9%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
mem: 132261196k total, 80358708k used, 51902488k free, 2489960k buffers
swap: 31455264k total, 2292k used, 31452972k free, 72454796k cached
pid user pr ni virt res shr s %cpu %mem time+ command
22305 oracle 20 0 884m 645m 618m s 0.0 0.5 0:00.39 ora_arc0_book
22303 oracle 20 0 859m 639m 634m s 0.0 0.5 0:00.82 oraclebook (description=(local=yes)(address=(protocol=beq)))
22291 oracle 20 0 859m 638m 632m s 0.0 0.5 0:00.66 ora_mmon_book
22323 oracle 20 0 858m 634m 628m s 0.0 0.5 0:00.40 ora_cjq0_book
22283 oracle 20 0 868m 628m 625m s 0.0 0.5 0:00.20 ora_lgwr_book
22277 oracle 20 0 860m 626m 618m s 0.0 0.5 0:00.17 ora_dbw0_book
22279 oracle 20 0 859m 625m 617m s 0.0 0.5 0:00.28 ora_dbw1_book
22281 oracle 20 0 859m 625m 617m s 0.0 0.5 0:00.26 ora_dbw2_book
22287 oracle 20 0 854m 625m 622m s 0.0 0.5 0:00.30 ora_smon_book
22289 oracle 20 0 855m 625m 622m s 0.0 0.5 0:00.27 ora_reco_book
22271 oracle 20 0 854m 624m 622m s 0.0 0.5 0:00.30 ora_dbrm_book
22307 oracle 20 0 876m 621m 618m s 0.0 0.5 0:00.23 ora_arc1_book
22259 oracle 20 0 855m 621m 619m s 0.0 0.5 0:00.49 ora_pmon_book
22293 oracle 20 0 854m 621m 618m s 0.0 0.5 0:00.37 ora_mmnl_book
22285 oracle 20 0 854m 620m 618m s 0.0 0.5 0:00.35 ora_ckpt_book
22273 oracle 20 0 854m 620m 617m s 0.0 0.5 0:00.31 ora_dia0_book
22275 oracle 20 0 853m 619m 617m s 0.0 0.5 0:00.25 ora_mman_book
22295 oracle 20 0 859m 619m 617m s 0.0 0.5 0:00.22 ora_d000_book
22261 oracle 20 0 853m 619m 617m s 0.0 0.5 0:00.20 ora_psp0_book
22269 oracle 20 0 853m 619m 617m s 0.0 0.5 0:00.24 ora_diag_book
22263 oracle -2 0 853m 619m 617m s 1.8 0.5 0:03.61 ora_vktm_book
22267 oracle 20 0 853m 619m 617m s 0.0 0.5 0:00.24 ora_gen0_book
22297 oracle 20 0 854m 618m 616m s 0.0 0.5 0:00.15 ora_s000_book
--//可以发现res消耗很大的内存.
这样页面表消耗如下:
$ cat /proc/meminfo | grep -i page
anonpages: 228148 kb
pagetables: 39968 kb
anonhugepages: 0 kb
hugepages_total: 104
hugepages_free: 104
hugepages_rsvd: 0
hugepages_surp: 0
hugepagesize: 2048 kb
--//重新启动看看:
sys@book> show parameter pre_page_sga
name type value
------------ ------- ------
pre_page_sga boolean false
$ cat /proc/meminfo | grep -i page
anonpages: 201812 kb
pagetables: 12536 kb
anonhugepages: 0 kb
hugepages_total: 309
hugepages_free: 98
hugepages_rsvd: 98
hugepages_surp: 205
hugepagesize: 2048 kb
--//pre_page_sga=false,使用hugepages.
top - 09:31:30 up 1065 days, 54 min, 1 user, load average: 0.12, 0.10, 0.09
tasks: 243 total, 1 running, 242 sleeping, 0 stopped, 0 zombie
cpu(s): 0.0%us, 0.0%sy, 0.0%ni, 99.9%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
mem: 132261196k total, 80083584k used, 52177612k free, 2489960k buffers
swap: 31455264k total, 2292k used, 31452972k free, 71826716k cached
pid user pr ni virt res shr s %cpu %mem time+ command
5459 oracle 20 0 69752 48m 716 s 0.3 0.0 19:08.01 tmux new-session -s oracle -n bashsqlplus -d
22431 oracle 20 0 859m 34m 29m s 0.0 0.0 0:00.60 oraclebook (description=(local=yes)(address=(protocol=beq)))
22417 oracle 20 0 859m 33m 28m s 0.0 0.0 0:00.47 ora_mmon_book
22451 oracle 20 0 858m 28m 23m s 0.0 0.0 0:00.19 ora_cjq0_book
22403 oracle 20 0 860m 22m 13m s 0.0 0.0 0:00.03 ora_dbw0_book
22405 oracle 20 0 859m 21m 13m s 0.0 0.0 0:00.02 ora_dbw1_book
22407 oracle 20 0 859m 21m 13m s 0.0 0.0 0:00.02 ora_dbw2_book
22413 oracle 20 0 854m 21m 18m s 0.0 0.0 0:00.06 ora_smon_book
22415 oracle 20 0 855m 20m 18m s 0.0 0.0 0:00.02 ora_reco_book
22397 oracle 20 0 854m 20m 17m s 0.0 0.0 0:00.02 ora_dbrm_book
22385 oracle 20 0 855m 17m 14m s 0.0 0.0 0:00.03 ora_pmon_book
22419 oracle 20 0 854m 16m 13m s 0.0 0.0 0:00.06 ora_mmnl_book
22409 oracle 20 0 868m 16m 14m s 0.0 0.0 0:00.04 ora_lgwr_book
22411 oracle 20 0 854m 16m 14m s 0.0 0.0 0:00.04 ora_ckpt_book
22435 oracle 20 0 876m 16m 13m s 0.0 0.0 0:00.02 ora_arc1_book
22399 oracle 20 0 854m 16m 13m s 0.0 0.0 0:00.08 ora_dia0_book
22433 oracle 20 0 876m 16m 13m s 0.0 0.0 0:00.02 ora_arc0_book
--//res仅仅20-30m上下.
总之:
我个人建议安装oracle,设置使用hugepages作为必要的步骤.设置pre_page_sga=true的情况下,更加必要.
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