[[PageOutline]]

= Performance Tuning =

== System Performance Tuning : Memory ==

 * Share Memory
{{{
echo "kernel.shmall = 796917578" >> /etc/sysctl.conf
echo "kernel.shmmax = 796917578" >> /etc/sysctl.conf
echo "kernel.shmmni = 4096"      >> /etc/sysctl.conf
}}}

== System Performance Tuning : File System ==

 * /etc/security/limits.conf - 每個程序(process)可以開啟檔案的個數(number limits of open files per process)
{{{
#!diff
--- /etc/security/limits.conf 2010-02-22 11:29:11.000000000 +0800
+++ /etc/security/limits.conf.new 2010-02-22 11:28:33.000000000 +0800
@@ -49,4 +49,6 @@
 #ftp             -       chroot          /ftp
 #@student        -       maxlogins       4
 
+*      soft        nofile        8192
+
 # End of file
}}}

== I/O Performance Tuning : NFS ==

 * NFS Tuning - /etc/fstab
{{{
192.168.0.111:/home /home nfs rw,bg,soft,intr,rsize=262144,wsize=262144 0 4
192.168.0.111:/opt  /opt  nfs ro,bg,soft,intr,rsize=262144,wsize=262144 0 4
192.168.0.111:/usr  /usr  nfs ro,bg,soft,intr,rsize=262144,wsize=262144 0 4
}}}

== Network Performance Tuning ==

 * TCP Tuning
{{{
echo 262144               > /proc/sys/net/core/rmem_default
echo 8388608              > /proc/sys/net/core/wmem_max
echo 8388608              > /proc/sys/net/core/rmem_max
echo "4096 87380 4194304" > /proc/sys/net/ipv4/tcp_rmem
echo "4096 65536 4194304" > /proc/sys/net/ipv4/tcp_wmem
}}}

== Power Management ==

 * 啟動 SATA ALPM 電源管理功能 - [http://packages.debian.org/powertop powertop] 提供之建議
{{{
echo min_power > /sys/class/scsi_host/host0/link_power_management_policy
}}}