NUMA, smp and AMD Intel

一直对NUMA体系结构没有直观的认识，看了FAQ: NUMA, SMP and AMDs Direct Connect Architecture才知道AMD Opteron双核采用的是NUMA结构。与SMP结构不同，主存不是通过Memory controller连接到CPUs，NUMA中不同的内存条直接连接到不同的CPU上。这样的好处在于可扩展性高，CPU可以独立访问属于自己的CPU，Memory controller不会成为系统的瓶颈。但缺点在于访问其它片的内存条用时会增加。这需要操作系统和进程进行优化才能发挥NUMA体系结构的好处。

目前Linux已经很好的支持SMP，有关NUMA的支持还不够完善。SUSE Linux Enterprise Server 9 队NUMA有较好的支持。

dynamips for CCIEs

Started in August of 2005 by Christophe Fillot, Dynamips is a Linux and Windows based application that is used to emulate the hardware of the Cisco 7200 and 3600 series routing platforms. Unlike traditional router “simulators" Dynamips allows you to boot real Cisco IOS software images and build complex network topologies to test the functionality of IOS on your desktop PC. As of November 2006 Dynamips currently supports Ethernet, Serial, ATM, and POS interfaces for the 7200 series routers and Ethernet, Serial, and Etherswitch modules for the 3600 series routers. Best of all Dynamips is open-source and free to download!