Create hugepages_settings.sh

hugepages_settings.sh

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+#!/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 and
+   you 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 -m
+
+
+Press 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" ];then
+    echo "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 $1}' | grep "[0-9][0-9]*"`
+do
+    MIN_PG=`echo "$SEG_BYTES/($HPG_SZ*1024)" | bc -q`
+    if [ $MIN_PG -gt 0 ]; then
+        NUM_PG=`echo "$NUM_PG+$MIN_PG+1" | bc -q`
+    fi
+done
+
+RES_BYTES=`echo "$NUM_PG * $HPG_SZ * 1024" | bc -q`
+
+# An SGA less than 100MB does not make sense
+# Bail out if that is the case
+if [ $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 -m
+
+of 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" ;;
+    '4.18') echo "Recommended setting: vm.nr_hugepages = $NUM_PG" ;;
+    '5.4') echo "Recommended setting: vm.nr_hugepages = $NUM_PG" ;;
+    *) echo "Kernel version $KERN is not supported by this script (yet). Exiting." ;;
+esac
+
+# End