为Oracle数据库在linux上配置hugepage内存管理---发表到鼎甲公众号
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为Oracle数据库在linux上配置hugepage内存管理---发表到鼎甲公众号
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文章目錄
- 配置HugePages的必要性
- 系統調整之前的狀態
-
- Oracle數據庫版本和參數
- 操作系統版本和參數
- 內核參數
- 檢查HugePages內存
- 檢查共享內存
- alert log中的警告
- 計算應配置的HugePages的大小
-
- 關閉AMM
- 計算HugePages大小的腳本
- 修改Linux內核參數
- use_large_pages參數的設置
- 修改完成后檢查
- 文章下方是我的微信，歡迎加我。👇
配置HugePages的必要性
HugePages是Linux內核2.6以后的版本上的一個內存管理特性，它將原來4K的內存頁管理單位改成更大頁的管理單位，通常是2M，極大地提高了大數據量時的內存使用效率。Oracle推薦在內存大于4GB的服務器上將SGA放入到HugePages內存中管理，現在的服務器基本100%符合這個條件。如果沒有配置成HugePages，那么每次數據庫啟動就會在alert log里面提示警告，看來Oracle真的對HugePages很在乎。本文舉例闡述這個特性的配置過程。
系統調整之前的狀態
Oracle數據庫版本和參數
SQL> show parameter large_pagesNAME TYPE VALUE
------------------------------------ ----------- ------------------------------
use_large_pages string TRUE
SQL> select * from v$version;BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
PL/SQL Release 11.2.0.4.0 - Production
CORE 11.2.0.4.0 Production
TNS for Linux: Version 11.2.0.4.0 - Production
NLSRTL Version 11.2.0.4.0 - Production操作系統版本和參數
[oracle@base-test-01 ~]$ grep Hugepagesize /proc/meminfo
Hugepagesize: 2048 kB
[oracle@base-test-01 ~]$ cat /etc/*release
BigCloud Enterprise Linux release 7.4.1807 (Core)
[oracle@base-test-01 ~]$ uname -r
3.10.0-693.el7.x86_64
內核參數
物理內存256G
[root@base-test-01 oracle]# sysctl -p
fs.aio-max-nr = 1048576
fs.file-max = 6815744
kernel.shmall = 67108864
kernel.shmmax = 256000000000
kernel.shmmni = 4096
kernel.sem = 250 32000 100 128
net.ipv4.ip_local_port_range = 9000 65500
net.core.rmem_default = 262144
net.core.rmem_max = 4194304
net.core.wmem_default = 262144
net.core.wmem_max = 1048576
vm.swappiness = 1檢查HugePages內存
目前內存里的Hugepage為零
$
AnonHugePages: 2156544 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB
檢查共享內存
[root@base-test-01 oracle]# ipcs -m
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x00000000 504037376 oracle 640 536870912 72
0x00000000 504070145 oracle 640 107911053312 72
0x42e38fd0 504102915 oracle 640 2097152 72
0x00000000 1212420 root 644 80 2
0x00000000 1245189 root 644 16384 2
0x00000000 1277958 root 644 280 2
0x00000000 297435143 root 600 524288 2 dest
0x00000000 508821513 root 600 832920 2 dest
0x00000000 297762851 root 600 4194304 2 dest
0x00000000 297861156 root 600 524288 2 dest
alert log中的警告
Starting ORACLE instance (normal)
************************ Large Pages Information *******************
Per process system memlock (soft) limit = 64 KBTotal Shared Global Region in Large Pages = 0 KB (0%)Large Pages used by this instance: 0 (0 KB)
Large Pages unused system wide = 0 (0 KB)
Large Pages configured system wide = 0 (0 KB)
Large Page size = 2048 KBRECOMMENDATION:Total System Global Area size is 101 GB. For optimal performance,prior to the next instance restart:1. Increase the number of unused large pages byat least 51713 (page size 2048 KB, total size 101 GB) system wide toget 100% of the System Global Area allocated with large pages2. Large pages are automatically locked into physical memory.Increase the per process memlock (soft) limit to at least 101 GB to lock100% System Global Area's large pages into physical memory
********************************************************************
計算應配置的HugePages的大小
關閉AMM
要將SGA放入到HugePages中，首先要關閉AMM(Automatic Memory Management)，方法是把兩個參數MEMORY_TARGET 和MEMORY_MAX_TARGET設為0。
SQL> alter system set MEMORY_MAX_TARGET=0 scope=spfile;
System altered.
SQL> alter system set memory_target=0 scope=spfile;
System altered.
SQL> alter system set sga_target=101G scope=spfile;
System altered.
計算HugePages大小的腳本
HugePages的大小需要根據OS的版本和SGA的大小進行計算得出，因為太小了SGA放不下，大了浪費。下面是計算腳本：
#!/bin/bash
#
# hugepages_settings.sh
#
# Linux bash script to compute values for the
# recommended HugePages/HugeTLB configuration
# on Oracle Linux
#
# 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 text
echo "
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 on Oracle Linux. 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 andyou should accommodate this while calculating the overall 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 version
KERN=`uname -r | awk -F. '{ printf("%d.%d\n",$1,$2); }'`# Find out the HugePage size
HPG_SZ=`grep Hugepagesize /proc/meminfo | awk '{print $2}'`
if [ -z "$HPG_SZ" ];thenecho "The hugepages may not be supported in the system where the script is being executed."exit 1
fi# Initialize the counter
NUM_PG=0# Cumulative number of pages required to handle the running shared memory segments
for SEG_BYTES in `ipcs -m | cut -c44-300 | awk '{print $1}' | grep "[0-9][0-9]*"`
doMIN_PG=`echo "$SEG_BYTES/($HPG_SZ*1024)" | bc -q`if [ $MIN_PG -gt 0 ]; thenNUM_PG=`echo "$NUM_PG+$MIN_PG+1" | bc -q`fi
doneRES_BYTES=`echo "$NUM_PG * $HPG_SZ * 1024" | bc -q`# An SGA less than 100MB does not make sense
# Bail out if that is the case
if [ $RES_BYTES -lt 100000000 ]; thenecho "***********"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 1
fi# Finish with results
case $KERN in'2.4') HUGETLB_POOL=`echo "$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" ;;'3.8') echo "Recommended setting: vm.nr_hugepages = $NUM_PG" ;;'3.10') echo "Recommended setting: vm.nr_hugepages = $NUM_PG" ;;'4.1') echo "Recommended setting: vm.nr_hugepages = $NUM_PG" ;;'4.14') echo "Recommended setting: vm.nr_hugepages = $NUM_PG" ;;*) echo "Kernel version $KERN is not supported by this script (yet). Exiting." ;;
esac# End
Recommended setting: vm.nr_hugepages = 51719
修改Linux內核參數
根據前面的計算結果，修改 /etc/sysctl.conf 加入vm.nr_hugepages = 51719。
[root@base-test-01 ~]# sysctl -p
fs.aio-max-nr = 1048576
fs.file-max = 6815744
kernel.shmall = 67108864
kernel.shmmax = 256000000000
kernel.shmmni = 4096
kernel.sem = 250 32000 100 128
net.ipv4.ip_local_port_range = 9000 65500
net.core.rmem_default = 262144
net.core.rmem_max = 4194304
net.core.wmem_default = 262144
net.core.wmem_max = 1048576
vm.swappiness = 1vm.nr_hugepages = 51719
修改/etc/security/limits.conf文件，以K為單位，必須大于sga_max_size,這里設定為256000000
[root@base-test-01 ~]# tail /etc/security/limits.conf
#@student - maxlogins 4# End of file
oracle soft nproc 2047
oracle hard nproc 16384
oracle soft nofile 1024
oracle hard nofile 65536
oracle soft stack 10240
oracle soft memlock 256000000
oracle hard memlock 256000000從新登入Oracle用戶，可以看到修改的參數起作用了。
[oracle@base-test-01 ~]$ ulimit -l
64
[oracle@base-test-01 ~]$ exit
logout
Connection to 192.168.87.205 closed.
scutech@Yao:~/software$ ssh oracle@192.168.87.205
oracle@192.168.87.205's password:
Last login: Wed Feb 26 17:09:31 2020
[oracle@base-test-01 ~]$ ulimit -l
256000000use_large_pages參數的設置
use_large_pages可設置的值包括：FALSE，ONLY，TRUE。
- false: Oracle實例將不會使用HugePages；
- true：Oracle實例將可以使用HugePages；
- only：Oracle實例只能使用HugePages；
這個參數默認是true，推薦將其配置成only，這樣將確保只有當數據庫實例的SGA從HugePages中獲得所有的內存才能被啟動，否則系統無法啟動。這里就避免實例的SGA運行在常規內存而DBA并不知道。
修改完成后檢查
sysctl -p 后系統已經分配大頁空間 （這段是后面補充的）
[root@localhost ~]# cat /proc/meminfo |grep -i HugePage
AnonHugePages: 0 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB
[root@localhost ~]# sysctl -p
fs.file-max = 6815744
kernel.sem = 250 32000 100 128
kernel.shmmni = 4096
kernel.shmall = 1073741824
kernel.shmmax = 4398046511104
kernel.panic_on_oops = 1
net.core.rmem_default = 262144
net.core.rmem_max = 4194304
net.core.wmem_default = 262144
net.core.wmem_max = 1048576
net.ipv4.conf.all.rp_filter = 2
net.ipv4.conf.default.rp_filter = 2
fs.aio-max-nr = 1048576
net.ipv4.ip_local_port_range = 9000 65500
vm.nr_hugepages = 97284
[root@localhost ~]# cat /proc/meminfo |grep -i HugePage
AnonHugePages: 0 kB
HugePages_Total: 97284
HugePages_Free: 97284
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB
[root@localhost ~]#
從新啟動數據庫后，檢查HugePages，發現已經使用。
# grep Huge /proc/meminfo
AnonHugePages: 2164736 kB
HugePages_Total: 51719
HugePages_Free: 46024
HugePages_Rsvd: 46018
HugePages_Surp: 0
Hugepagesize: 2048 kB
Oracle的alert log中已經沒有關于大頁的警告了，相反是SGA已經納入HugePages管理的提示信息。
Thu Feb 27 10:31:43 2020
Starting Oracle instance (normal)
************************ Large Pages Information *******************
Per process system memlock (soft) limit = 244 GBTotal Shared Global Region in Large Pages = 101 GB (100%)Large Pages used by this instance: 51713 (101 GB)
Large Pages unused system wide = 6 (12 MB)
Large Pages configured system wide = 51719 (101 GB)
Large Page size = 2048 KB
********************************************************************
文章下方是我的微信，歡迎加我。👇
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