learn superficial

In order to thoroughly understand what makes Linux tick and why it works so well on a wide variety o systems, you need to delve deep into the heart of the kernel.

thoroughy   adv.  十分地, 彻底地
tick        n.    滴答声, 记号, 勾号, 扁虱
            v.    滴答地响, 标以记号, 作滴答声
delve       v.    钻研

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Probing beyond superficial features, the authors offer valuable insights to people who want to know how things really work inside their machine.

superficial     adj.  表面的, 肤浅的, 浅薄的

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Preemptive kernel
    When compiled with the "Preemptible Kernel" option, Linux 2.6 can arbitrarily
interleave execution flows while they are in privileged mode. Besides Linux 2.6, a few other conventional, general-purpose Unix systems, such as Solaris and Mach 3.0 , are fully preemptive kernels. SVR4.2/MP introduces some fixed preemption points as a method to get limited preemption capability.

非抢占（Non-Preemptive）内核中如果任务不主动放弃，就不会被其他的高优先极任务抢掉对于CPU的控
制。

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Linux 2.6 supports symmetric multiprocessing (SMP) for different memory models, including NUMA: the system can use multiple processors and each processor can handle any task there is no discrimination among them.

    SMP的全称是"对称多处理"（Symmetrical Multi-Processing）技术，是指在一个计算机上汇集

了一组处器(多CPU),各CPU之间共享内存子系统以及总线结构。

    在安装时，客户没有选择安装kernel-smp，系统会缺省安装为单处理器核心，用户可以通过添加

多处理器心模组，将系统升级。

具体步骤:
1、启动Red Hat Linux 6.2，以root身份登录，进入字符界面。
2、将光盘插入光驱，#mount /mnt/cdrom，将光驱挂载。
3、#cd /mnt/cdrom/Redhat/RPMS，进入模组所在路径。
4、#rpm --install kernel-smp-2.2.14-5.0.i386.rpm，加载多处理器（smp）模块。
5、#mkinitrd -v -f /boot/initrd-2.2.14-5.0smp.img 2.2.14-5.0smp，创建初始化程序。
6、#vi /etc/lilo.conf，添加多处理器启动选项，例如
    image=/boot/vmlinuz-2.2.14-5.0smp
    label=smp
    initrd=/boot/initrd-2.2.14-5.0smp.img
    read-only
    root=/dev/sda2
7、#lilo -v，重新启动机器，在“boot:”出现后，键入“smp”回车，进入多处理器核心。

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    This chapter deals with addressing techniques. Luckily, an operating system is not forced to keep track of physical memory all by itself; today's microprocessors include several hardware circuits to make memory management both more efficient and more robust so that programming errors cannot cause improper accesses to memory outside the program.

robust        adj.    精力充沛的
improper      adj.    不适当的, 不合适的, 不正确的, 不合礼仪的, 不适宜