redhat设置 huge page步骤

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Configuring HugePages on Linux

Complete the following steps to configure HugePages on the computer:

• 
  Edit the memlock setting in the /etc/security/limits.conf file. The memlock setting is specified in KB and set slightly lesser than the installed RAM. For example, if you have 64GB RAM installed, add the following entries to increase the max locked memory limit:
  
  *   soft   memlock    60397977
  *   hard   memlock    60397977
  
  You can also set the memlock value higher than your SGA requirements.
  
  
• 
  Login as the oracle user again and run the ulimit -l command to verify the new memlock setting:
  
  $ ulimit -l
  60397977
  
• 
  Run the following command to display the value of Hugepagesize variable:
  
  $ grep Hugepagesize /proc/meminfo
  
• 
  Complete the following procedure to create a script that computes recommended values for hugepages configuration for the current shared memory segments:
  
  Note:
  
  Following is an example that may require modifications.
  
  
  
  
  • 
    Create a text file named hugepages_settings.sh.
    
    
  • 
    Add the following content in the file:
    
    #!/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.
    # 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'}`
    # Start from 1 pages to be on the safe side and guarantee 1 free HugePage
    NUM_PG=1
    # Cumulative number of pages required to handle the running shared memory segments
    for SEG_BYTES in `ipcs -m | awk {'print $5'} | grep "[0-9][0-9]*"`
    do
    MIN_PG=`echo "$SEG_BYTES/($HPG_SZ*1024)" | bc -q`
    if [ $MIN_PG -gt 0 ]; then
    NUM_PG=`echo "$NUM_PG+$MIN_PG+1" | bc -q`
    fi
    done
    # 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" ;;
    *) echo "Unrecognized kernel version $KERN. Exiting." ;;
    esac
    # End
    
  • 
    Run the following command to change the permission of the file:
    
    $ chmod +x hugepages_settings.sh
    
  
  
• 
  Run the hugepages_settings.sh script to compute the values for hugepages configuration:
  
  $ ./hugepages_settings.sh
  
• 
  Set the following kernel parameter:
  
  # sysctl -w vm.nr_hugepages=value_displayed_in_step_5
  
• 
  To make the value of the parameter available for every time you restart the computer, edit the /etc/sysctl.conf file and add the following entry:
  
  vm.nr_hugepages=value_displayed_in_step_5
  
• 
  Restart the server.
  
  Note:
  
  To check the available hugepages, run the following command:
  $ grep Huge /proc/meminfo