Linux 2.6.31内核优化-1
虚拟机
Virtualbox 3.1.4
CPU
Core 2 Duo P9500 2.53G
磁盘
虚拟
内存
分了1G物理内存
网卡
虚拟
其他
USB，串口，显卡，声卡全关
作者是在虚拟机中编译的内核，如果你与作者的运行环境不同，则本文档中的部分描述可能会与你的实际情况有一定出入。
不过，相信大部分用户在看到选项释义时，能做出适合自己的选择。
?
说明
下列选项中，通过?"// "?注释的行
通过红色?"<==="?注释的行，代表内核默认开启，本文档推荐关闭的选项，释义部分会给出关闭的理由。
?
?General setup? --->
[ ] Prompt for development and/or incomplete code/drivers?<===?显示尚在开发中或尚未完成的代码和驱动.?我不是内核或驱动开发人员。
()? Local version - append to kernel release
[ ] Automatically append version information to the version string
Kernel compression mode (Bzip2)? --->?<===?对比默认的Gzip，Bzip2拥有更高的压缩比
[*] Support for paging of anonymous memory (swap)
[*] System V IPC
[*] BSD Process Accounting
[ ]? BSD Process Accounting version 3 file format
[ ] Export task/process statistics through netlink (EXPERIMENTAL)?<===?体验类选项一律关
[ ] Auditing support?<===?给SELinux提供支持。我的使用场景主要是开发应用程序，不需要那么高的安全性，另外安全总是以牺牲性能为代价
RCU Subsystem? ---> //?非对称读写锁系统?是一种新的kernel锁机制，适用于读多写少环境
RCU Implementation (Classic RCU)? ---> <===?选择标准的RCU系统，?tree-base是给拥有大规模CPU集群的SMP系统用的
< > Kernel .config support
(18) Kernel log buffer size (16 => 64KB, 17 => 128KB)
[] Control Group support? ---><=== cgroups支持，文档资料，cgroups主要作用是给进程分组，并可以动态调控进程组的CPU占用率。比如A进程分到apple组，给予20%CPU占用率，E进程分easy组，给予50%CPU占用率，最高100%。我目前没有此类应用场景，用到时会选择将其编译进去。
[] Kernel->user space relay support (formerly relayfs)?<===?在某些文件系统上(比如debugfs)提供从内核空间向用户空间传递大量数据的接口，我目前没有此类应用场景
-*- Namespaces support
[]?? UTS namespace?<===?我没有已安装的应用程序要用到?UTS ns
[]?? IPC namespace?<===?我没有已安装的应用程序要用到?IPC ns
[] Initial RAM filesystem and RAM disk (initramfs/initrd) support?<===?用于在真正内核装载前，做一些操作（俗称两阶段启动），比如加载module，mount一些非root分区，提供灾难恢复shell环境等，资料，我是期望直接从kernel image直接启动，所以没选它
[*] Optimize for size
[ ] Configure standard kernel features (for small systems)? --->
-*-?? Load all symbols for debugging/ksymoops
[ ]???? Do an extra kallsyms pass?<===?除非你在kallsyms中发现了bug并需要报告这个bug才打开该选项
Performance Counters? --->?
[*] Kernel Performance Counters // CPU?性能监听器，包括?CPU同一时间执行指令数，cache miss数，分支预测失败次数(Branch misprediction)。调优其他程序时或许会用到，比如JVM
[ ] Strip assembler-generated symbols during link
[ ] Disable heap randomization
Choose SLAB allocator (SLUB (Unqueued Allocator))? --->
[ ] Profiling support (EXPERIMENTAL)?<===?我不是内核开发人员，不需要profile内核
[] Activate markers?<===?一种运行时状态分析诊断工具，类似?instrumentation，资料，我用不到
[ ] Kprobes?<===?我不是内核开发人员，不需要调试内核
GCOV-based kernel profiling? --->
[ ] Enable gcov-based kernel profiling
?
[*] Enable loadable module support? ---> //?我很少使用dynamic module loading，所以，下面的选项只留一个unloading即可（默认）
--- Enable loadable module support
[ ]?? Forced module loading
[*]?? Module unloading
[ ]?? Module versioning support
[ ]?? Source checksum for all modules
?
-*- Enable the block layer? --->
--- Enable the block layer
[*]?? Support for large (2TB+) block devices and files //?大硬盘支持，SATA设备如果不选，会发生?kernel panic，具体原因未知
[ ]?? Block layer SG support v4?<===?支持通用scsi块设备第4版，我用的是SATA
[ ]?? Block layer data integrity support
IO Schedulers? ---> // IO调度器支持，不同程序可以会选用不同的调度策略，这里我们不要动他
<*> Anticipatory I/O scheduler
<*> Deadline I/O scheduler
<*> CFQ I/O scheduler
??? Default I/O scheduler (CFQ)? --->
?
Processor type and features? --->
[*] Tickless System (Dynamic Ticks) // CPU节能，动态时间片意思是当CPU处于空闲时，降低内核定时器的轮询频率
[*] High Resolution Timer Support //?我有的时候要测试?Real Time JVM，希望内核能支持这种高响应速度的内核定时器，一般用户可关闭
[*] Symmetric multi-processing support
[ ] Support sparse irq numbering?<===?如果你想支持大量CPU，又想使用较低的内核内存占用，请启用它。我只有单块CPU
[*] Enable MPS table?//?让多核/多CPU系统支持ACPI
[ ] Support for big SMP systems with more than 8 CPUs
[ ] Support for extended (non-PC) x86 platforms?<===?我是X86平台，不需要再支持其他平台
[*] Single-depth WCHAN output //?跟?proc?相关的最好不要关
[ ] Paravirtualized guest support? --->
--- Paravirtualized guest support
[ ] Memtest
Processor family (Core 2/newer Xeon)? --->?<===?这里请选择对应的CPU，我是?core 2 duo
[ ] Generic x86 support?<===?通用x86支持,?如果你的CPU能够在上述"Processor family"中找到就别选了
[*] HPET Timer Support
(4) Maximum number of CPUs?<===?我的CPU是双核，算上超线程HT最多虚拟4颗逻辑CPU，所以我选4?，默认是8
[*] SMT (Hyperthreading) scheduler support
[*] Multi-core scheduler support
Preemption Model (Voluntary Kernel Preemption (Server))? --->?<===?这里我选择了Server，它最贴近我的使用场景
[*] Reroute for broken boot IRQs //?防止同时收到多个boot IRQ(中断)时，系统混乱
[*] Machine Check Exception
[ ]?? Use legacy machine check code (will go away)
[*]?? Intel MCE features
[ ]?? AMD MCE features?<===?我是intel CPU
[ ] Support for old Pentium 5 / WinChip machine checks
< > Machine check injector support
< > Toshiba Laptop support
< > Dell laptop support
[ ] Enable X86 board specific fixups for reboot?<===?修正某些旧x86主板的重起bug,这种主板基本绝种了
<*> /dev/cpu/microcode - microcode support
[*]?? Intel microcode patch loading support
[ ]?? AMD microcode patch loading support?<===?我是intel CPU
<*> /dev/cpu/*/msr - Model-specific register support
<*> /dev/cpu/*/cpuid - CPU information support
< > /sys/kernel/debug/x86/cpu/* - CPU Debug support
High Memory Support (4GB)? --->
(4096) Low address space to protect from user allocation
[*] Allocate 3rd-level pagetables from highmem?<===?在内存很多(大于4G)的机器上将用户空间的页表放到高位内存区,以节约宝贵的低端内存?，我只虚拟了1G
[ ] Check for low memory corruption?<===?低位内存脏数据检查，默认是每60秒检查一次。一般这种脏数据是因某些Bios处理不当引起的。资料链接。我信任我目前的虚拟bios版本
[] Reserve low 64K of RAM on AMI/Phoenix BIOSen?<===?我不是?AMI/Phoenix BIOS
[ ] Math emulation
[ ] MTRR (Memory Type Range Register) support?<===?我没用?X windows
[ ]?? MTRR cleanup support
[ ]?? x86 PAT support?<===?我没用?X windows
[ ] EFI runtime service support?<===?我机器是BIOS引导的，用不到EFI(Extensible Firmware Interface)，如果你有兴趣体验EFI，可以在Virtualbox中开启
[] Enable seccomp to safely compute untrusted bytecode?<===?只有嵌入式系统可以不选
[ ] Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)
Timer frequency (300 HZ)? --->?<=== Server场景建议设为300hz，减少内核事件响应速度，提高程序吞吐量，桌面场景可以保持不变
[ ] kexec system call?<===?我没有运行时替换内核的需求
[ ] kernel crash dumps?<===?内核崩溃时，dump运行时信息。就算crash了，我也不会去调试内核的core dump
[ ] Build a relocatable kernel?<===?官方说明?（建立一个移动的内核，并增加10%的内核尺寸，运行时会被丢弃），我认为没实质性的作用
(0x1000000) Physical address where the kernel is loaded
[] Support for hot-pluggable CPUs?<===?热拔插CPU，我用不到
[ ] Compat VDSO support
[ ] Built-in kernel command line
?
Power management and ACPI options? --->
[*] Power Management support
[ ]?? Power Management Debug Support?<===?不想调试ACPI
[ ]???? Verbose Power Management debugging
[ ] Suspend to RAM and standby?<===?我是用来跑server，一般不需要待机
[ ] Hibernation (aka 'suspend to disk')??<===?我是用来跑server，一般不需要休眠
[*] ACPI (Advanced Configuration and Power Interface) Support? --->
[*]?? Deprecated /proc/acpi files
[*]?? Deprecated power /proc/acpi directories
[*]?? Future power /sys interface
[*]?? Deprecated /proc/acpi/event support
< >?? AC Adapter?<===?我不需要从AC与Battery之间做切换
< >?? Battery?<===?没有电池
< >?? Button?<===?没有Fn快捷键
-*-?? Video
<*>?? Fan
<*>?? Processor
<*>???? Thermal Zone
(0)?? Disable ACPI for systems before Jan 1st this year
[ ]?? Debug Statements
< >?? PCI slot detection driver
< >?? Smart Battery System
??? CPU Frequency scaling? --->
[*] CPU Frequency scaling
[ ]?? Enable CPUfreq debugging?<===?我不需要调试?CPUfreq
< >?? CPU frequency translation statistics
Default CPUFreq governor (performance)? --->?<===?默认用?performance高性能的CPU调频方式
<*>?? 'performance' governor
< >?? 'powersave' governor
<>?? 'userspace' governor for userspace frequency scaling?<===?既允许手动调整cpu频率,也允许用户空间的程序动态的调整cpu频率(需要额外的调频软件,比如cpufreqd)??我只用performance
<>?? 'ondemand' cpufreq policy governor?<=== "周期性的考察CPU负载并自动的动态调整cpu频率"，我只用?performance
<>?? 'conservative' cpufreq governor
*** CPUFreq processor drivers ***
<*>?? ACPI Processor P-States driver
< >?? AMD Mobile K6-2/K6-3 PowerNow!
< >?? AMD Mobile Athlon/Duron PowerNow!
< >?? AMD Opteron/Athlon64 PowerNow!
< >?? Cyrix MediaGX/NatSemi Geode Suspend Modulation
< >?? Intel Enhanced SpeedStep (deprecated)
< >?? Intel Speedstep on ICH-M chipsets (ioport interface)
< >?? Intel Pentium 4 clock modulation
< >?? Transmeta LongRun
< >?? VIA Cyrix III Longhaul
?
Bus options (PCI etc.)? --->
[*] PCI support
PCI access mode (Any)? --->
[*] PCI Express support
[*]?? Root Port Advanced Error Reporting support?//?硬件驱动会负责发送错误信息
[ ]???? PCI Express ECRC settings control
< >???? PCIE AER error injector support
[*] Message Signaled Interrupts (MSI and MSI-X)
[ ] Enable deprecated pci_find_* API
[ ] PCI Debugging
< > PCI Stub driver
[*] Interrupts on hypertransport devices
[ ] PCI IOV support
[ ] ISA support
[ ] MCA support
< > NatSemi SCx200 support
[ ] One Laptop Per Child support
< > PCCard (PCMCIA/CardBus) support? --->?<===?一般笔记本电脑会配备PCCard接口(无线网卡之类的)，看你的硬件和使用场景吧。虽然我也是NB，但我从来不用PCMCIA
< > Support for PCI Hotplug? --->?<===?我没有要热拔插PCI设备的需求
?
Executable file formats / Emulations? --->
[*] Kernel support for ELF binaries
[*] Write ELF core dumps with partial segments
< > Kernel support for a.out and ECOFF binaries
<*> Kernel support for MISC binaries
?
[*] Networking support? --->
Networking options? --->
<*> Packet socket
[*]?? Packet socket: mmapped IO
<*> Unix domain sockets
<*> Transformation user configuration interface
< > PF_KEY sockets
[*] TCP/IP networking
[*]?? IP: multicasting
[*]?? IP: advanced router
Choose IP: FIB lookup algorithm (choose FIB_HASH if unsure) (FIB_HASH)? --->
[*]?? IP: policy routing
[*]?? IP: equal cost multipath
[*]?? IP: verbose route monitoring
[ ]?? IP: kernel level autoconfiguration?<===?我很少用网络引导OS，内核级别的网络配置对我无用。
[ ]???? IP: DHCP support
[ ]???? IP: BOOTP support
[ ]???? IP: RARP support
< >?? IP: tunneling
< >?? IP: GRE tunnels over IP
[*]?? IP: multicast routing
[*]???? IP: PIM-SM version 1 support
[*]???? IP: PIM-SM version 2 support
[ ]?? IP: ARP daemon support
[ ]?? IP: TCP syncookie support (disabled per default)?<===?抵抗SYN flood攻击，我是开发机，暂不考虑安全特性
< >?? IP: AH transformation
< >?? IP: ESP transformation
?< >?? IP: IPComp transformation
< >?? IP: IPsec transport mode
< >?? IP: IPsec tunnel mode
< >?? IP: IPsec BEET mode
[*]?? Large Receive Offload (ipv4/tcp)
< >?? INET: socket monitoring interface
[ ]?? TCP: advanced congestion control? --->?<===?高级拥塞控制,如果没有特殊需求(比如无线网络)就别选了
< >?? The IPv6 protocol? --->?<===?我暂时没有要支持IPV6的需求
[ ]?? NetLabel subsystem support?<=== NetLabel子系统,?为诸如CIPSO与RIPSO之类能够在分组信息上添加标签的协议提供支持，我用不到
[ ] Security Marking?<===?对网络包进行安全标记,类似于nfmark,但主要是为安全目的而设计,?安全特性，我暂时不考虑
[ ] Network packet filtering framework (Netfilter)? --->?<===?我不打算使用防火墙，要用到时再编译进去
< > Asynchronous Transfer Mode (ATM)
< > 802.1d Ethernet Bridging
< > 802.1Q VLAN Support
< > DECnet Support
< > ANSI/IEEE 802.2 LLC type 2 Support
< > The IPX protocol
< > Appletalk protocol support
< > Phonet protocols family
[ ] QoS and/or fair queueing? --->??<===?通过IPRoute切换网络设备上的Qos策略，我不打算使用IP路由
[ ] Data Center Bridging support
Network testing? --->
[ ]?? Amateur Radio support? --->?<===?我没有无线电
< >?? CAN bus subsystem support? --->
< >?? IrDA (infrared) subsystem support? --->
< >?? Bluetooth subsystem support? --->
[ ]?? Wireless? --->?<===?我没有使用无线网卡
< >?? RF switch subsystem support? --->?<===?我没有RF切换设备
