Shulou(Shulou.com)06/02 Report--

Preface

For HugePages and Oracle database optimization of Linux system, you can refer to Xiong Ye's previous article. The relevant concepts are introduced very clearly:

Optimization of Linux large memory page Oracle database

The purpose of this paper is to quickly configure HugePages on Linux systems.

Test environment: RHEL6.8 + 512G physical memory; Oracle 11.2.0.4 SGA=400G.

1. Set memlock without limit

In the / etc/security/limits.conf configuration file, set the oracle user memlock without restrictions:

Vi / etc/security/limits.conf

Oracle soft memlock unlimitedoracle hard memlock unlimited

two。 Set reasonable vm.nr_hugepages

In the / etc/sysctl.conf configuration file, set a reasonable vm.nr_ hugepages value.

You can get the suggested value directly by running the hugepages_settings.sh script provided by MOS 401749.1.

The content of the hugepages_settings.sh script:

#! / 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 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 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 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 HPG_SZ 2);}' `# Find out the HugePage sizeHPG_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 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 $1}'| grep "[0-9] [0-9] *" `doMIN_PG= `echo "$SEG_BYTES/ ($HPG_SZ*1024)" | bc-q`if [$MIN_PG-gt 0] ThenNUM_PG= `echo "$NUM_PG+$MIN_PG+1" | bc-q`fixes res _ 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]; 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 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 ";;' 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";; esac# End

Run the script directly to get the corresponding advice:

-- when the launched instance sets SGA_MAX_SIZE=12G, give the suggestion: Recommended setting: vm.nr_hugepages = 6148 SGA_MAX_SIZE=400G-when the launched instance sets SGA_MAX_SIZE=400G, give the suggestion: Recommended setting: vm.nr_hugepages = 204805mi-when the instance is not started, it will send an error message: * ERROR * 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

Here I append the recommended value vm.nr_hugepages = 204805 to the / etc/sysctl.conf configuration file, and then perform the sysctl-p effective configuration.

3. Confirm that the HugePages setting is successful

To view the information about HugePages, notice that the HugePages_ Total value is 204805 of the previously set value:

Grep Huge / proc/meminfo

# grep Huge / proc/meminfo AnonHugePages: 0 kBHugePages_Total: 204805HugePages_Free: 168475HugePages_Rsvd: 168471HugePages_Surp: 0Hugepagesize: 2048 kB

When the database starts, there will be "Large Pages Information" in the corresponding alert log:

Wed Nov 14 14:38:12 2018Starting ORACLE instance (normal) * Large Pages Information * Per process system memlock (soft) limit = UNLIMITEDTotal Shared Global Region in Large Pages = 400 GB (100%) Large Pages used by this instance: 204801 (400 GB) Large Pages unused system wide = 4 (8192 KB) Large Pages configured system wide = 204805 (400 GB) Large Page size = 2048 KB****

At this point, you can confirm that the HugePages setting is successful.

Summary

The above is the whole content of this article, I hope that the content of this article has a certain reference and learning value for your study or work, if you have any questions, you can leave a message and exchange, thank you for your support.

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