在Oracle 11.2.0.3.0上开启大页(hugepages)的详细解析
来源:互联网 发布:云计算培训机构 编辑:程序博客网 时间:2024/06/04 18:27
转载请注明出处:http://blog.csdn.net/guoyjoe/article/details/17138391
什么时侯使用大页呢,当你主机的物理内存为64G,设SGA>=32G时,建议开启大页,步骤如下:
1、 关闭Oracle Database 11g中的AMM(Automatic Memory Management),即把两个参数MEMORY_TARGET / MEMORY_MAX_TARGET设为0
如果设考数 MEMORY_MAX_TARGET为0不成功,那么请考参http://blog.csdn.net/guoyjoe/article/details/12845965
gyj@OCM> show parameter memory_max_targetNAME TYPE VALUE------------------------------------ ----------- ------------------------------memory_max_target big integer 0gyj@OCM> show parameter memory_targetNAME TYPE VALUE------------------------------------ ----------- ------------------------------memory_target big integer 0
2、参考metalink(文档 ID 401749.1)提供的脚本,计算hugepages的大小
[oracle@mydb admin]$ vi /u01/app/oracle/product/11.2.0/rdbms/admin/hugepages_settings.sh
#!/bin/bash## hugepages_settings.sh## Linux bash script to compute values for the# recommended HugePages/HugeTLB configuration## Note: This script does calculation for all shared memory# segments available when the script is run, no matter it# is an Oracle RDBMS shared memory segment or not.## This script is provided by Doc ID 401749.1 from My Oracle Support # http://support.oracle.com# Welcome textecho "This script is provided by Doc ID 401749.1 from My Oracle Support (http://support.oracle.com) where it is intended to compute values for the recommended HugePages/HugeTLB configuration for the current shared memory segments. Before proceeding with the execution please note following: * For ASM instance, it needs to configure ASMM instead of AMM. * The 'pga_aggregate_target' is outside the SGA and you should accommodate this while calculating SGA size. * In case you changes the DB SGA size, as the new SGA will not fit in the previous HugePages configuration, it had better disable the whole HugePages, start the DB with new SGA size and run the script again.And make sure that: * Oracle Database instance(s) are up and running * Oracle Database 11g Automatic Memory Management (AMM) is not setup (See Doc ID 749851.1) * The shared memory segments can be listed by command: # ipcs -mPress Enter to proceed..."read# Check for the kernel versionKERN=`uname -r | awk -F. '{ printf("%d.%d\n",$1,$2); }'`# Find out the HugePage sizeHPG_SZ=`grep Hugepagesize /proc/meminfo | awk '{print $2}'`if [ -z "$HPG_SZ" ];then echo "The hugepages may not be supported in the system where the script is being executed." exit 1fi# Initialize the counterNUM_PG=0# Cumulative number of pages required to handle the running shared memory segmentsfor SEG_BYTES in `ipcs -m | cut -c44-300 | awk '{print $1}' | grep "[0-9][0-9]*"`do MIN_PG=`echo "$SEG_BYTES/($HPG_SZ*1024)" | bc -q` if [ $MIN_PG -gt 0 ]; then NUM_PG=`echo "$NUM_PG+$MIN_PG+1" | bc -q` fidoneRES_BYTES=`echo "$NUM_PG * $HPG_SZ * 1024" | bc -q`# An SGA less than 100MB does not make sense# Bail out if that is the caseif [ $RES_BYTES -lt 100000000 ]; then echo "***********" echo "** ERROR **" echo "***********" echo "Sorry! There are not enough total of shared memory segments allocated for HugePages configuration. HugePages can only be used for shared memory segments that you can list by command: # ipcs -mof a size that can match an Oracle Database SGA. Please make sure that: * Oracle Database instance is up and running * Oracle Database 11g Automatic Memory Management (AMM) is not configured" exit 1fi# Finish with resultscase $KERN in '2.2') echo "Kernel version $KERN is not supported. Exiting." ;; '2.4') HUGETLB_POOL=`echo "$NUM_PG*$HPG_SZ/1024" | bc -q`; echo "Recommended setting: vm.hugetlb_pool = $HUGETLB_POOL" ;; '2.6') echo "Recommended setting: vm.nr_hugepages = $NUM_PG" ;;esac# End
3、对hugepages_settings.sh这个脚本授可执行的权限
[oracle@mydb admin]$ chmod +x hugepages_settings.sh
4、执行hugepages_settings.sh,计算hugepages的值为1028M
[oracle@mydb admin]$ ./hugepages_settings.sh
This script is provided by Doc ID 401749.1 from My Oracle Support (http://support.oracle.com) where it is intended to compute values for the recommended HugePages/HugeTLB configuration for the current shared memory segments. Before proceeding with the execution please note following: * For ASM instance, it needs to configure ASMM instead of AMM. * The 'pga_aggregate_target' is outside the SGA and you should accommodate this while calculating SGA size. * In case you changes the DB SGA size, as the new SGA will not fit in the previous HugePages configuration, it had better disable the whole HugePages, start the DB with new SGA size and run the script again.And make sure that: * Oracle Database instance(s) are up and running * Oracle Database 11g Automatic Memory Management (AMM) is not setup (See Doc ID 749851.1) * The shared memory segments can be listed by command: # ipcs -mPress Enter to proceed...Recommended setting: vm.nr_hugepages = 1028
得出大页的大小为1028页(注:一页为2M,这个值不可改,1028*2M=2056M),实际上hugepages与参数sga_max_size有关,比sga_max_size的值稍微大一点点(比SGA_MAX_SIZE最少要多加一页,2M的页不要分配超过sga_max_size太多,会造成内存的浪费):
gyj@OCM> show parameter sga_max_size
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
sga_max_size big integer 2G
5、设置hugepages,在内核参数中添加一行,vi /etc/sysctl.conf
vm.nr_hugepages = 1028
[root@mydb ~]# sysctl -p
net.ipv4.ip_forward = 0net.ipv4.conf.default.rp_filter = 1net.ipv4.conf.default.accept_source_route = 0kernel.sysrq = 0kernel.core_uses_pid = 1net.ipv4.tcp_syncookies = 1kernel.msgmnb = 65536kernel.msgmax = 65536kernel.shmmax = 68719476736kernel.shmall = 4294967296fs.file-max = 6815744vm.nr_hugepages = 1028
7、别忘记设定/etc/security/limits.conf文件,以K为单位,必须大于sga_max_size,这里设定为2056000
[root@mydb ~]# vi /etc/security/limits.conf
oracle soft memlock 2056000
oracle hard memlock 2056000
8、检查limits是否正确
[root@mydb ~]# su - oracle
[oracle@mydb ~]$ ulimit -l
2056000
sys@OCM> exitDisconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit ProductionWith the Partitioning, OLAP, Data Mining and Real Application Testing options[oracle@mydb ~]$ exitlogoutYou have new mail in /var/spool/mail/root[root@mydb ~]# su - oracle[oracle@mydb ~]$ sqlplus / as sysdbaSQL*Plus: Release 11.2.0.3.0 Production on Thu Dec 5 10:56:20 2013Copyright (c) 1982, 2011, Oracle. All rights reserved.Connected to:Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit ProductionWith the Partitioning, OLAP, Data Mining and Real Application Testing optionssys@OCM> shutdown immediate;Database closed.Database dismounted.ORACLE instance shut down.sys@OCM> startupORACLE instance started.Total System Global Area 2137886720 bytesFixed Size 2230072 bytesVariable Size 1409288392 bytesDatabase Buffers 603979776 bytesRedo Buffers 122388480 bytesDatabase mounted.Database opened.
10、查看大页,已被使用
[oracle@mydb ~]$ watch -n1 'cat /proc/meminfo |grep -i HugePage'
Every 1.0s: cat /proc/meminfo |grep -i HugePage Thu Dec 5 11:09:06 2013 HugePages_Total: 1028 HugePages_Free: 869 HugePages_Rsvd: 842 Hugepagesize: 2048 kB注:
HugePages_Total: 1028 ---总共1028页
HugePages_Free: 869 ---空闲548页,即当前大页被使用了1028-869=159页,即被用了159*2M=118M,小于sga_target。
HugePages_Rsvd: 842 ---操作系统承诺给Oracle预留842页,即842*2M=1684M(1684+118==SGA_MAX_SIZE)
Hugepagesize: 2048 kB --每页是2M,不可修改
使用了hugepage之后,SGA就默认pin在内存里了,那么就不用lock sga了。接下来我们研究一下参数:pre_page_sga,这个参数默认是false,我把它打开。
sys@OCM> alter system set pre_page_sga=true scope=spfile; System altered. sys@OCM> show parameter sga NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ lock_sga boolean FALSE pre_page_sga boolean TRUE sga_max_size big integer 2G sga_target big integer 1GHugePages_Total: 1028 ---总共1028页
HugePages_Free: 548 ---空闲548页,即当前大页被使用了1028-548=480页,即被用了480*2M=960M,约等于sga_target,参数pre_page_sga起作用了。
HugePages_Rsvd: 521 ---操作系统承诺给Oracle预留521页,即521*2M=1042M(理解为sga_max_size-sga_target)
Hugepagesize: 2048 kB --每页是2M,不可修改
参考metalink:USE_LARGE_PAGES To Enable HugePages (文档 ID 1392497.1)
For 11.2.0.2 and further, the Oracle Database Server has added a new parameter that helps managing the hugepages for use by the database.
The initialization parameter that was added is USE_LARGE_PAGES.
USE_LARGE_PAGES parameter has these possible values: "true" (default), "only", "false".
1. The default value of "true" preserves the current behavior of trying to use hugepages if they are available on the OS.
In 11.2.0.2 if there are not enough hugepages, only small pages will be used for SGA memory. This may lead to ORA-4030 errors due to the remaining hugepages going unused and more memory being used by the kernel for page tables.
In 11.2.0.3 the behavior was changed such that Oracle will now allocate what it can of the SGA in hugepages and if it runs out, it will allocate the rest of the SGA using small pages. With this new behavior additional shared memory segments are an expected side effect. Part of the change is to ensure that each shared memory segment making up the SGA only contains sub-areas with an identical alignment requirement - hence the SGA will spread over more separate SHM segments. In this supported mixed page mode the database will exhaust the available hugepages, before switching to regular sized pages.
2. Setting it to "false" means do not use hugepages
3. A setting of "only" means do not start up the instance if hugepages cannot be used for the whole memory (to avoid an out-of-memory situation).
补充关于内存申请的OverCommit:
Linux有三种OverCommit机制,可以通过:/proc/sys/vm/overcommit_memory来配置,三种配置的具体含义:
0:启发式策略,后果比较严重的Overcommit将不能成功,而轻微的Overcommit将被允许。
1:永远允许Overcommit,这种策略适合那些不能承受内存分配失败的应用,比如某些科学计算应用。
2:永远禁止Overcommit,在这个情况下,系统所能分配的内存不会超过swap+RAM*系数(/proc/sys/vm /overcmmit_ratio,默认50%,你可以调整),如果这么多资源已经用光,那么后面任何尝试申请内存的行为都会返回错误,这通常意味着此时 没法运行任何新程序。
[root@mydb vm]# cd /proc/sys/vm [root@mydb vm]# ls block_dump flush_mmap_pages min_free_kbytes overcommit_memory swappiness dirty_background_ratio hugetlb_shm_group min_slab_ratio overcommit_ratio swap_token_timeout dirty_expire_centisecs laptop_mode min_unmapped_ratio pagecache vfs_cache_pressure dirty_ratio legacy_va_layout mmap_min_addr page-cluster zone_reclaim_mode dirty_writeback_centisecs lowmem_reserve_ratio nr_hugepages panic_on_oom drop_caches max_map_count nr_pdflush_threads percpu_pagelist_fraction
假设操作系统只有1000M内存,有个应用请求操作系统需要1200M内存,操作系统会承诺给1200M,即由OverCommit承诺,这时还没有真正分配空间。
- 在Oracle 11.2.0.3.0上开启大页(hugepages)的详细解析
- 在Oracle 11.2.0.3.0上开启大页(hugepages)的详细解析
- Linux下配置(大页)Hugepages
- 在linux下为oracle开启大页(hugepage)
- 大页内存(HugePages)在通用程序优化中的应用
- 大页内存(HugePages)在通用程序优化中的应用
- 大页内存(HugePages)在通用程序优化中的应用
- 未开启HugePages ORACLE session剧增时引起的一次悲剧
- Redis在linux上的安装,配置,后台开启,详细
- 大页(huge pages) 系列四 ---Transparent HugePages
- 在RHEL6.7上开启大页内存
- Linux HugePages及MySQL 大页配置
- Linux HugePages及MySQL 大页配置
- oracle11g 在 16核 64g 的pc server上利用hugePages提升性能
- 大内存( Very Large Memory)和 大页( HugePages)系列二--配置大页
- 在 SLES11, RHEL6, RHEL7, OL6, OL7 and UEK2 Kernels中请务必要禁用Transparent HugePages (透明的大页内存)
- 在ubuntu上安装oracle JDK的详细步骤
- 大内存( Very Large Memory)和 大页( HugePages)系列一
- maven的简单使用方法,添加公共jar和第三方jar包
- 【HDU-oj】-4920-Matrix multiplication(矩阵,裸)
- 关于hololens调用讯飞语音sdk问题汇总
- Angular开发者指南(一)入门介绍
- poj2251(翻译)
- 在Oracle 11.2.0.3.0上开启大页(hugepages)的详细解析
- 734C Anton and Making Potions
- CentOs 6.5下安装jdk1.7
- i18next的使用
- js基础5应用案例
- Spring中容器的作用域
- Bone Collector_HDU
- ROS探索总结(十四)——move_base(路径规划)
- 列表——更改的是谁