#!/bin/sh

# Copyright (c) 2011 Sean Chittenden <sean@chittenden.org>. Public domain.
#
# GOAL: Provide sane kernel tuning parameters for dedicated PostgreSQL
# servers running on FreeBSD, Darwin or Leenox. Tune the shared memory
# settings to 50% of the available pages
#
# If this doesn't work or you have an adjustment you'd like to see made,
# please send it along to sean@chittenden.org.
#
# TODO: Can we auto-tune kern.ipc.semmap (aka $semmap)?

# Get the size of a page
page_size=`getconf PAGE_SIZE`

OSTYPE=`uname -s`

# Deal with GNUtards
if [ "${OSTYPE}" = 'linux' ]; then
    OSTYPE="Linux"
fi

# Get the number of pages available on this host
if [ "${OSTYPE}" = "Linux" ]; then
    phys_pages=`getconf _PHYS_PAGES`
elif [ "${OSTYPE}" = "FreeBSD" ]; then
    phys_pages=`sysctl -n hw.availpages`
elif [ "${OSTYPE}" = "Darwin" ]; then
    phys_pages=$((`sysctl -n hw.memsize` / ${page_size}))
fi


if [ -z "$page_size" -o -z "$phys_pages" ]; then
    printf "ERROR: Unable to determine the page_size or number of pages available on this system\n"
    printf "HINT: Run this script with -x and figure out which one didn't work\n"
    printf "BONUS POINTS: Submit a correction to sean@chittenden.org\n"
    exit 1
fi

# Calcs ala sh(1). Use 50% of available pages for shm.
shmall=`expr $phys_pages / 2`       # Max shared segment size (bytes)
shmmax=`expr $shmall \* $page_size` # Max num of shared mem segments (pages)
semmap=256


if [ "${OSTYPE}" = "Linux" ]; then
    printf "# Append the following to /etc/sysctl.conf and then run: sysctl -p\n"
    printf "kernel.shmmax = %d\n" $shmmax
    printf "kernel.shmall = %d\n" $shmall
elif [ "${OSTYPE}" = "FreeBSD" ]; then
    printf "# Append the following to /etc/sysctl.conf and then run\n"
    printf "# '/etc/rc.d/sysctl start'\n"
    printf "kern.ipc.shmmax=%d\n" $shmmax
    printf "kern.ipc.shmall=%d\n" $shmall
    printf "kern.ipc.semmap=%d\n" $semmap
    printf "\n"
    printf "One time use: \n"
    printf "sudo sysctl -w kern.ipc.shmmax=%d\n" $shmmax
    printf "sudo sysctl -w kern.ipc.shmall=%d\n" $shmall
    printf "sudo sysctl -w kern.ipc.semmap=%d\n" $semmap
    printf "\n"
    printf "Add the following to /boot/loader.conf\n"
    printf "These changes require a restart to go in to effect:\n"
    printf "kern.ipc.semmni=256\n"
    printf "kern.ipc.semmns=512\n"
    printf "kern.ipc.semmnu=256\n"
elif [ "${OSTYPE}" = 'Darwin' ]; then
    printf "# Append the following to /etc/sysctl.conf and either restart or\n"
    printf "# run the following sysctl commands by hand\n"
    printf "kern.ipc.shmmax=%d\n" $shmmax
    printf "kern.ipc.shmall=%d\n" $shmall
    printf "\n"
    printf "One time use: \n"
    printf "sudo sysctl -w kern.ipc.shmmax=%d\n" $shmmax
    printf "sudo sysctl -w kern.ipc.shmall=%d\n" $shmall
fi