使用Preload 给Ubuntu系统加速

本教程旨在说明如何在 Ubuntu 9.04 系统上安装 Preload ，并使用它为系统提速。Preload 是一个自适应预读守护进程。它监控用户运行的应用程序，并且分析这些数据，预测用户可能运行的程序，并读取这些程序的二进制文件及其依赖文件到系统内存，以达到加速启动的时间。

本文当不做任何形式的担保！我不保证它能在你的系统上正常工作！

安装 Preload

要安装 Preload ，首先打开终端 （应用程序/附件/终端），然后输入：

sudo aptitude install preload

来安装 Preload 。

安装完成。Preload 将在后台静静运行。如果你想改变 Preload 的行为，你可以编辑它的配置文件 /etc/preload.conf 。这是它的默认配置：

sudo gedit /etc/preload.conf

[model]

# cycle:
#
# This is the quantum of time for preload. Preload performs
# data gathering and predictions every cycle. Use an even
# number.
#
# Note: Setting this parameter too low will may reduce the
# system performance and stability.
#
# unit: seconds
# default: 20
#
cycle = 20

# usecorrelation:
#
# Whether correlation coefficient should be used in the prediction
# algorithm. There are arguments both for and against using it.
# Currently it’s believed that using it results in more accurate
# prediction. The option may be removed in the future.
#
# default: true
usecorrelation = true

# minsize:
#
# Minimum sum of the length of maps of the process for
# preload to consider tracking the application.
#
# Note: Setting this parameter too high will make preload less
# effective, while setting it too low will make it eat
# quadratically more resources, as it tracks more processes.
#
# unit: bytes
# default: 2000000
#
minsize = 2000000

#
# The following control how much memory preload is allowed to use
# for preloading in each cycle. All values are percentages and are
# clamped to -100 to 100.
#
# The total memory preload uses for prefetching is then computed using
# the following formulae:
#
# max (0, TOTAL * memtotal + FREE * memfree) + CHACED * memcached
# where TOTAL, FREE, and CACHED are the respective values read at
# runtime from /proc/meminfo.
#

# memtotal: precentage of total memory
#
# unit: signed_integer_percent
# default: -10
#
memtotal = -10

# memfree: precentage of free memory
#
# unit: signed_integer_percent
# default: 100
#
memfree = 100

# memcached: precentage of cached memory
#
# unit: signed_integer_percent
# default: 30
#
memcached = 30

###########################################################################

[system]

# doscan:
#
# Whether preload should monitor running processes and update its
# model state. Normally you do want that, that’s all preload is
# about, but you may temporarily want to turn it off for various
# reasons like testing and only make predictions. Note that if
# scanning is off, predictions are made based on whatever processes
# have been running when preload started and the list of running
# processes is not updated at all.
#
# default: true
doscan = true

# dopredict:
#
# Whether preload should make prediction and prefetch anything off
# the disk. Quite like doscan, you normally want that, that’s the
# other half of what preload is about, but you may temporarily want
# to turn it off, to only train the model for example. Note that
# this allows you to turn scan/predict or or off on the fly, by
# modifying the config file and signalling the daemon.
#
# default: true
dopredict = true

# autosave:
#
# Preload will automatically save the state to disk every
# autosave period. This is only relevant if doscan is set to true.
# Note that some janitory work on the model, like removing entries
# for files that no longer exist happen at state save time. So,
# turning off autosave completely is not advised.
#
# unit: seconds
# default: 3600
#
autosave = 3600

# mapprefix:
#
# A list of path prefixes that controll which mapped file are to
# be considered by preload and which not. The list items are
# separated by semicolons. Matching will be stopped as soon as
# the first item is matched. For each item, if item appears at
# the beginning of the path of the file, then a match occurs, and
# the file is accepted. If on the other hand, the item has a
# exclamation mark as its first character, then the rest of the
# item is considered, and if a match happens, the file is rejected.
# For example a value of !/lib/modules;/ means that every file other
# than those in /lib/modules should be accepted. In this case, the
# trailing item can be removed, since if no match occurs, the file is
# accepted. It’s advised to make sure /dev is rejected, since
# preload doesn’t special-handle device files internally.
#
# default: (empty list, accept all)
mapprefix = /usr;/lib;!/

# exeprefix:
#
# The syntax for this is exactly the same as for mapprefix. The only
# difference is that this is used to accept or reject binary exectuable
# files instead of maps.
#
# default: (empty list, accept all)
exeprefix = !/usr/sbin;!/usr/local/sbin;/usr;!/

如果你更改了配置，你需要重启 Preload ：

sudo /etc/init.d/preload restart


本文来自：http://huzuofeiwei.com/2009/07/speed-up-your-system-with-preload-on-ubuntu-904.html