Slow Pacman Workaround(< 3.5!!!)

gistfile1.txt

This is obsolete with the new pacman version 3.5!

Pacman (arch linux) uses a file based database with a lot
of small files. Some filesystems are awfully slow when 
accessing lots of small files, in general this is not 
that great of a deal because most of the applications 
store their information with more sense. Pacman doesn't 
care (it is a long well known problem), which means that 
sometimes you have to wait minutes before a search query 
completes (pacman -Ss).

# strace pacman -Ss rails 2> pacman_sS_rails.log
community/vim-rails 4.3-2
   A Vim plugin for enhanced Ruby on Rails application development
# egrep '^open\(' pacman_sS_rails.log | wc
10259

This script creates a loopfs with reiserfs (the best fs 
for many small files) and copies the pacman "db" into it.

pacman (< 3.5!!!)

#!/bin/bash

# new pacman versions are fast without this (< 3.5!!!) 

# stop: umount /var/lib/pacman; losetup -d /dev/loop0

DATA="/var/lib/pacman"
VDISK="/var/lib/pacman.loopfs"
LOOP_DEV="/dev/loop0"

# create the loopfs
if [ ! -f $VDISK ];
then
  echo "Create loopfs!"
  dd if=/dev/zero of=$VDISK bs=1024 count=524288
  losetup $LOOP_DEV $VDISK
  mkfs.reiserfs $LOOP_DEV
else
  echo "Start loopfs"
  losetup $LOOP_DEV $VDISK
fi

# move the pacman directory to _backup if not already done
if [ ! -d "${DATA}_backup" ]; then
  mv ${DATA} ${DATA}_backup
  mkdir ${DATA}
fi

# mount loopfs
mount -o noatime $LOOP_DEV ${DATA}

# copy the files from the backup if not already done
if [ ! -d "${DATA}/local" ]; then
  echo "Copy backup to loopfs mount"
  cp -aux ${DATA}_backup/* ${DATA}
fi