阅读笔记:Dual Core Opterons
Dual Core Opterons
按：想通过google找到Solaris是否支持NUMA的答案，因此偶然间搜索到了Eric的blog,里面不少有趣的东西，值得一读。
So it's no secret that AMD and Intel are in a mad sprint（奔跑）to the finish for dual-core x86 chips. The offical AMD roadmap, as well as public demos have all shown AMD well on track. The latest tidbits（花絮） of information indicate Linux is up and running on these dual-core systems. Very cool.
Given our close relationship with AMD and the sensitive nature of
hardware plans, I'll refrain from（避免）saying what we may or may not have
running in our labs. But Solaris has some great features that make it
well-suited for these dual core chips. First of all, Solaris 10 has had
support for both Chip Multi Threading (hyperthreading) and Chip Multi
Processing (multi core) for about a year and half now. Solaris has also
been NUMA-aware for much longer (with the current lgroups coming in
mid-2001, or Solaris 9). I'm sure AMD has made these cores appear as
two processesors for legacy purposes, but with a little cpuid tweaks, we'll see them as sibling（姐弟） cores and get all the benefits inherent in Solaris 10 CMP.
注解：
1.Solaris
10是支持超线程和多内核CPU的，如果打开BIOS的超线程的设置的开关，用psrinfo就可以看到CPU个数是CPU*超线程数。多内核的CPU也
是如此。假设8内核的CPU每个内核包含4个超线程，那么用psrinfo观察一个CPU就是32个。
2.Solaris在版本9的时候，就已经支持了NUMA架构。
Despite this, the NUMA system in Solaris is undergoing（经历） drastic（激烈的）
change due to the Opteron memory architecture. While Solaris is
NUMA-aware, it uses a simplistic（过分简化） memory heirarchy based on the physical
architecture of Sun's high end SPARC systems. We have the notion of a
"locality（位置） group", which represents the logical relationship of CPUs and
memory. Currently, there are only two notions（概念） of locality - "near" and
"far". Solaris tries its best to keep logically connected memory and
processes in the same locality group. On Opteron, things get a bit more
complicated due to the integrated memory controller and HyperTransport
layout. On 4-way machines the processors are laid out in a square（正方形）, and
on 8-way machines we have a ladder（梯状） formation. Memory transfers must
pass through neighboring memory controllers, so now memory could be
"near", "far", or "farther". We're revamping（修改） the current lgroup system
to support arbitrary（任意的） memory heirachies, which should produce some nice
performance gains on 4- and 8-way Opteron machines. Hopefully one of
the NUMA folks will blog some more detailed information once this
project integrates.
注解：
1. Opteron的内存架构是NUMA的，它集成了内存控制器，采用了AMD开发的HyperTransport总线技术。
2. Solaris原有的NUMA的支持是为支持SPARC高端而设计的，内存和CPU的位置可以被简单的分为近和远两种。
3. Solaris针对Opteron对NUMA支持部分进行重新设计并优化。
In conclusion: Opterons are cool, but dual-core Opterons are cooler. And Solaris will rip on both of them.