Difference between revisions of "Centos-optimization"

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= CentOS Optimizations =

== Disk ==

In order to speedup the disk management, some values are added to each `ext3` partition on the terminal.

The reference site is located at [[http://wiki.centos.org/HowTos/Disk_Optimization]]

LABEL=/ / ext3 defaults,noatime,data=writeback,commit=120 1 1

tmpfs /dev/shm tmpfs defaults 0 0

devpts /dev/pts devpts gid=5,mode=620 0 0

sysfs /sys sysfs defaults 0 0

proc /proc proc defaults 0 0

/customswap swap swap defaults 0 0

==== noatime ====

Don't write access time

==== data=writeback ====

The data order is not preserved when writes to disk. Just after set this value and before restart the terminal run the following command to avoid goes into read-only mode.

tune2fs -o +journal_data_writeback /dev/hda1

==== commit=120 ====

Set the time to sync data and metadata.

== Solid State Disk ==

Usually the IDE SSD are slower that the SATA SSD, and some times could even be slower than the regular IDE. To speed up a bit, we can apply the changes mentioned above, but also scheduler can be changed in the following way:

# echo deadline > /sys/block/sda/queue/scheduler

# echo 1 > /sys/block/sda/queue/iosched/fifo_batch

All the other options for the scheduler can be displayed with the command

# cat /sys/block/sda/queue/scheduler

but usually <code>noop</code> and <code>deadline</code> are the 2 that works well with SDD.

To make permanent this change, add the <code>elevator=deadline</code> at the end of the kernel line in <tt>/boot/menu/grub.conf</tt>

== System ==

In <tt>/etc/sysctl.conf</tt> set the vualue

kernel.shmmax = 63554432

to increase ''Maximum shared segment''.

== Boot ==

Reduce boot time passing the known values to the kernel, the site that references.

Optimizations can be found at [[[Media:centos-optimization$embedded_linux_optimizations.pdf | Free Electrons - Embedded Linux Optimizations]]]

# grub.conf generated by anaconda

#

# Note that you do not have to rerun grub after making changes to this file

# NOTICE: You do not have a /boot partition. This means that

# all kernel and initrd paths are relative to /, eg.

# root (hd0,0)

# kernel /boot/vmlinuz-version ro root=/dev/hda1

# initrd /boot/initrd-version.img

#boot=/dev/hda

default=0

timeout=0

splashimage=(hd0,0)/boot/grub/splash.xpm.gz

hiddenmenu

password --md5 $1$/omJBwhD$phlKUXHDZI6BMLkNSfNgD/

title Bashlinux

root (hd0,0)

kernel /boot/vmlinuz-2.6.18-53.el5 ro root=LABEL=/ rhgb vga=792 lpj=998235 reboot=soft quiet

initrd /boot/initrd-2.6.18-53.el5.img

==== lpj ====

Loops per jiffy can be obtained from <tt>/var/log/messages</tt>

==== reboot=soft ====

When reboots, the firmware will be skipped.

==== quiet ====

Doesn't log all the boot messages to the <tt>stdout</tt>