一、 概述
squid是一款優秀的open source的代理服務器軟件，可以運行於多種系統平台上，但是同其他商業化的產品相比，其缺點也是很明顯的，那就是它的命中率和效率相對低下。
本文主要討論在不改變硬件條件之下，通過以下手段對squid進行性能優化：
1． 編譯一個高效的、精簡的新內核；
2． 對Cache分區采用reiserfs日志文件系統；
3． 重新編譯squid；
4． 優化squid配置；
對於優化的效果，我使用大名鼎鼎的cacheflow公司的測試工具——cfmc進行測試比較：
首先用cfmc自帶的一個腳本，從squid.conf的Access.log中抽出RUL，然後以這些RUL為依據進行測試。
服務器配置：
型號：HP LH3
CPU：PII450
內存：256MB 100MHz ECC SDRAM DIMM
硬盤：9.1GB Hot-Swap Ultra2 Hard Disk
網卡：Ethernet EXPress PRO 100 10/100M X 2
操作系統：RedHat 7.1
優化前測試結果：
Iteration 0: Cumulative statistics; 933 seconds elapsed
Total objects: 72599, total object size: 513211102 bytes
Average object size: 7069 bytes
Average object response time: 2707 milliseconds
Objects per second: 77.81
Bytes per second: 550065, min: 550065, max: 879873
URLs discarded due to socket or connection failures: 6955
Redirections: 1017, Cookied objects: 1036
Pragma no-cache objects: 1656, Non-200 HTTP response codes: 2505
優化後測試結果：
Iteration 0: Cumulative statistics; 688 seconds elapsed
Total objects: 72599, total object size: 403833100 bytes
Average object size: 5562 bytes
Average object response time: 1890 milliseconds
Objects per second: 105.52
Bytes per second: 586966, min: 586966, max: 995582
URLs discarded due to socket or connection failures: 16372
Redirections: 1658, Cookied objects: 1000
Pragma no-cache objects: 1454, Non-200 HTTP response codes: 3132
通過對以上測試結果的比較，我們可以看出：
優化後的Objects per second增加了35.6％，Average object response time減少了43.2％，對整體性能的提升還是比較明顯的。
二、 編譯新內核
我們采取這樣的方式來編譯內核：取消內核的模塊支持，將服務器所有的硬件驅動編譯到內核中，此外還要注意將對reiserfs文件系統的支持也編譯到內核中，從而在提供系統性能的同時增加系統安全性。在2.4.10以上的版本中，已經內置了對reiserfs文件系統的支持。
首先從http://www.kernel.org/pub/Linux/kernel/v2.4/下載linux-2.4.12.tar.gz，這是當前最新的內核。
然後解開內核文件：
tar xvzf linux-2.4.12.tar.gz
進入新生成的目錄並執行：
cd linux
make mrproper
make config
根據我的服務器的配置，我選擇這樣編譯內核：
* Code maturity level options
Prompt for development and/or incomplete code/drivers (CONFIG_EXPERIMENTAL) [Y/n/?]
* Loadable module support
Enable loadable module support (CONFIG_MODULES) [N/y/?]
* Processor type and features
Processor family (386, 486, 586/K5/5x86/6x86/6x86MX, Pentium-Classic, Pentium-MM
X, Pentium-Pro/Celeron/Pentium-II, Pentium-III/Celeron(Coppermine), Pentium-4, K
6/K6-II/K6-III, Athlon/Duron/K7, Crusoe, Winchip-C6, Winchip-2, Winchip-2A/Winch
ip-3, CyrixIII/C3) [Pentium-Pro/Celeron/Pentium-II]
* General setup
Networking support (CONFIG_NET) [Y/n/?]
PCI support (CONFIG_PCI) [Y/n/?]
PCI access mode (BIOS, Direct, Any) [Any]
defined CONFIG_PCI_GOANY
PCI device name database (CONFIG_PCI_NAMES) [Y/n/?]
System V IPC (CONFIG_SYSVIPC) [Y/n/?]
Sysctl support (CONFIG_SYSCTL) [Y/n/?]
Kernel core (/proc/kcore) format (ELF, A.OUT) [ELF]
defined CONFIG_KCORE_ELF
* Plug and Play configuration
Plug and Play support (CONFIG_PNP) [Y/n/?]
* Block devices
Normal PC floppy disk support (CONFIG_BLK_DEV_FD) [Y/n/?]
* Networking options
Kernel/User netlink socket (CONFIG_NETLINK) [Y/n/?]
Routing messages (CONFIG_RTNETLINK) [Y/n/?]
Network packet filtering (replaces ipchains) (CONFIG_NETFILTER) [Y/n/?]
Unix domain sockets (CONFIG_UNIX) [Y/n/?]
TCP/IP networking (CONFIG_INET) [Y/n/?]
IP: advanced router (CONFIG_IP_ADVANCED_ROUTER) [Y/n/?]
IP: policy routing (CONFIG_IP_MULTIPLE_TABLES) [Y/n/?]
IP: use netfilter MARK value as routing key (CONFIG_IP_ROUTE_FWMARK) [Y/n/?]
IP: fast network address translation (CONFIG_IP_ROUTE_NAT) [Y/n/?]
IP: equal cost multipath (CONFIG_IP_ROUTE_MULTIPATH) [Y/n/?]
* IP: Netfilter Configuration
Connection tracking (required for masq/NAT) (CONFIG_IP_NF_CONNTRACK) [Y/n/?]
FTP protocol support (CONFIG_IP_NF_FTP) [Y/n/?]
IP tables support (required for filtering/masq/NAT) (CONFIG_IP_NF_IPTABLES) [Y/n/?]
limit match support (CONFIG_IP_NF_MATCH_LIM99v) [Y/n/?]
Multiple port match support (CONFIG_IP_NF_MATCH_MULTIPORT) [Y/n/?]
Connection state match support (CONFIG_IP_NF_MATCH_STATE) [Y/n/?]
Packet filtering (CONFIG_IP_NF_FILTER) [Y/n/?]
Full NAT (CONFIG_IP_NF_NAT) [Y/n/?]
REDIRECT target support (CONFIG_IP_NF_TARGET_REDIRECT) [Y/n/?]
LOG target support (CONFIG_IP_NF_TARGET_LOG) [Y/n/?]
ATA/IDE/MFM/RLL support (CONFIG_IDE) [Y/n/?]
* IDE, ATA and ATAPI Block devices
Enhanced IDE/MFM/RLL disk/cdrom/tape/floppy support (CONFIG_BLK_DEV_IDE) [Y/n/?]
Include IDE/ATA-2 DISK support (CONFIG_BLK_DEV_IDEDISK) [Y/n/?]
Use multi-mode by default (CONFIG_IDEDISK_MULTI_MODE) [Y/n/?]
Include IDE/ATAPI CDROM support (CONFIG_BLK_DEV_IDECD) [Y/n/?]
* SCSI support
SCSI support (CONFIG_SCSI) [Y/n/?]
* SCSI support type (disk, tape, CD-ROM)
SCSI disk support (CONFIG_BLK_DEV_SD) [Y/n/?]
Maximum number of SCSI disks that can be loaded as modules (CONFIG_SD_EXTRA_DEVS) [8]
* Some SCSI devices (e.g. CD jukebox) support multiple LUNs
Enable extra checks in new queueing code (CONFIG_SCSI_DEBUG_QUEUES) [Y/n/?]
* SCSI low-level drivers
AMI MegaRAID support (CONFIG_SCSI_MEGARAID) [Y/n/?]
SYM53C8XX SCSI support (CONFIG_SCSI_SYM53C8XX) [Y/n/?]
default tagged command queue depth (CONFIG_SCSI_NCR53C8XX_DEFAULT_TAGS) [4]
maximum number of queued commands (CONFIG_SCSI_NCR53C8XX_MAX_TAGS) [32]
synchronous transfers frequency in MHz (CONFIG_SCSI_NCR53C8XX_SYNC) [80]
* Network device support
Network device support (CONFIG_NETDEVICES) [Y/n/?]
* Ethernet (10 or 100Mbit)
Ethernet (10 or 100Mbit) (CONFIG_NET_ETHERNET) [Y/n/?]
EISA, VLB, PCI and on board controllers (CONFIG_NET_PCI) [Y/n/?]
EtherExpressPro/100 support (CONFIG_EEPRO100) [Y/n/?]
* Input core support
Input core support (CONFIG_INPUT) [Y/n/?]
Keyboard support (CONFIG_INPUT_KEYBDEV) [Y/n/?]
* Character devices
Virtual terminal (CONFIG_VT) [Y/n/?]
Support for console on virtual terminal (CONFIG_VT_CONSOLE) [Y/n/?]
Standard/generic (8250/16550 and compatible UARTs) serial support (CONFIG_SERIAL) [Y/n/?]
Unix98 PTY support (CONFIG_UNIX98_PTYS) [Y/n/?]
Maximum number of Unix98 PTYs in use (0-2048) (CONFIG_UNIX98_PTY_COUNT) [8]
* File systems
Reiserfs support (CONFIG_REISERFS_FS) [Y/n/?]
ISO 9660 CDROM file system support (CONFIG_ISO9660_FS) [Y/n/?]
/proc file system support (CONFIG_PROC_FS) [Y/n/?]
/dev/pts file system for Unix98 PTYs (CONFIG_DEVPTS_FS) [Y/n/?]
* Console drivers
VGA text console (CONFIG_VGA_CONSOLE) [Y/n/?]
這裡需要說明的是：如果要使用透明代理模式，要仔細選擇Netfilter，因為我們還得用iptables來重定向tcp包，以滿足透明代理的要求。
假如您的服務器配置與我的不同，只需要更改相應的硬件配置參數即可，
Support for console on virtual terminal (CONFIG_VT_CONSOLE) [Y/n/?]
Standard/generic (8250/16550 and compatible UARTs) serial support (CONFIG_SERIAL) [Y/n/?]
Unix98 PTY support (CONFIG_UNIX98_PTYS) [Y/n/?]
Maximum number of Unix98 PTYs in use (0-2048) (CONFIG_UNIX98_PTY_COUNT) [8]
* File systems
Reiserfs support (CONFIG_REISERFS_FS) [Y/n/?]
ISO 9660 CDROM file system support (CONFIG_ISO9660_FS) [Y/n/?]
/proc file system support (CONFIG_PROC_FS) [Y/n/?]
/dev/pts file system for Unix98 PTYs (CONFIG_DEVPTS_FS) [Y/n/?]
* Console drivers
VGA text console (CONFIG_VGA_CONSOLE) [Y/n/?]
這裡需要說明的是：如果要使用透明代理模式，要仔細選擇Netfilter，因為我們還得用iptables來重定向tcp包，以滿足透明代理的要求。
假如您的服務器配置與我的不同，只需要更改相應的硬件配置參數即可，
* File systems
Reiserfs support (CONFIG_REISERFS_FS) [Y/n/?]
ISO 9660 CDROM file system support (CONFIG_ISO9660_FS) [Y/n/?]
/proc file system support (CONFIG_PROC_FS) [Y/n/?]
/dev/pts file system for Unix98 PTYs (CONFIG_DEVPTS_FS) [Y/n/?]
* Console drivers
VGA text console (CONFIG_VGA_CONSOLE) [Y/n/?]
這裡需要說明的是：如果要使用透明代理模式，要仔細選擇Netfilter，因為我們還得用iptables來重定向tcp包，以滿足透明代理的要求。
假如您的服務器配置與我的不同，只需要更改相應的硬件配置參數即可，
