- 论坛徽章:
- 0
|
首先声明这是网上找到的一篇文章,作者信息如下:
© Alrad Imaging
Alrad Instruments Ltd, Alder House, Turnpike Road Industrial Estate
Newbury Berkshire RG14 2NS
Tel: +44 (0)1635 30345 fax: +44(0)1635 32630
www.alrad.com e-mail support@alrad.co.uk
文章正文
What’s wrong with PCI?
PCI, or Peripheral Component Interconnect was developed by Intel in 1992 and is the local bus used in most PCs until know.PCI uses a shared bus topology to allow for communication among the different devices on the bus i.e. the different PCI devices are attached to the same bus, and share the bandwidth. This diagram explains the situation.
图一
It can run at clock speeds of 33 or 66 MHz. At 32 bits and 33 MHz, it will yield a throughput rate of 133 MBps which is too slow to cater for the latest frame grabbers especially as even this is shared with other PCI devices.
PCI怎么了?
PCI,或者外围设备互联是Intel在1992年开发的并且在现在的大多数PC上仍然应用的局域总线。PCI用了一个共享总线拓扑结构来提供在总线上不同设备之间的通信。比如说不同的PCI设备连在同一个总线上并且共享带宽。图一对这种情况有一个解释。
图一
它可以运行在33或者66MHz的时钟频率下。在32位和33MHz下,它可以产生133M比特每秒的吞吐率,但是这个速率对现在的架构特别还是跟其它PCI设备共享的架构来说太慢了。
Why is PCI-X an improvement?
PCI-X stands for PCI Extended.
The PCI-X spec essentially doubled the bus width from 32 bits to 64 bits, thereby increasing bandwidth. The PCI's basic clock rate is increased to 66MHz with a 133MHz variety on the high end, providing another boost to the bandwidth and bringing it up to 1GB/s (at 133MHz).
Having said this PCI-X still suffers from the problem of Shared bus topology and also the faster a bus runs, the more sensitive it becomes to background noise.For this reason manufacturing standards for high-speed buses are exceptionally strict and therefore expensive. The PCI-x slot is physically longer that a PCI Slot.
为什么PCI-x有所提升?
PCI-x代表PCI扩展。
PCI-x从本质上来说把总线的宽度有32位提高到了两倍64位,因此提高了带宽。PCI的基本时钟频率提高到了66MHz和133MHz之间的几种,提供了另外一种增加带宽的能力并且把它提高到了1GB/s(在133MHz下)。
已经提到的PCI-x虽然是比较快的总线但是仍然有共享总线这种问题,the more sensitive it becomes to background noise. 因为这个原因这种高速总线的制造标准异常的严格并且因此很贵。PCI-x在物理上要比PCI插槽要长。
Is PCI-E any better?
PCI-E stands fro PCI Express and is also known as 3GIO (Third Generation I/O)。 The most fundamental improvement is the adoption of point-to-point bus topology.
In a point-to-point bus topology, a shared switch replaces the shared bus as the single shared resource by means of which all of the devices communicate. Unlike in a shared bus topology, where the devices must collectively arbitrate among themselves for use of the bus, each device in the system has direct and exclusive access to the switch.
PCI-e有没有更好一些?
PCI-e是PCI Express它被认为是3GIO(第三带I/O)。最基础的提高是它采用了点到点的总线结构。
在点到点这种总线结构中,一个共享的switch作为单独的共享资源代替了原来共享的总线,这意味所有的设备之间可以通信。不像在共享总线这种拓扑结构中所有的设备必须经过判断才能使用总线,PCI-e可以使在系统中的所有设备直接并且唯一的访问switch。
The connections between the devices and the switch is called a link and each link is consists of a number of lanes. Each lane is able to carry data in both directions. The gain in bandwidth is considerable as each lane can carry 2.5Gps in each direction.
The PCI Express slot is available in versions of from 1 lane to 32 lanes and are called x1, x2, x4, x8, x16 and x32. The slot and connector are different lengths for each version.
设备和switch之间的连接被称为链接,每一个链接包括一个数字通道。每一个通道在所有的方向上都可以携带数据。带宽上的增长相当于每一个通道在每个方向上可以携带 2.5Gps。
PCI Express 插槽可以从1 个通道到32个通道,这被称为x1, x2, x4, x8, x16 and x32。每个不同的版本插槽和连接器的长度都不同。
Is PCI obsolete?
At least for the time being, PCs are being produced with PCI-X and PCI-E slots as additional to PCI slots.
PCI 会过时吗?
至少暂时,被生产的带有PCI-X和PCI-E插槽的PCs额外还带有PCI插槽。
Summary of bandwidth capabilities
Type Bandwidth Mbytes/s
PCI 32 bit / 33 MHz 132
PCI 64 bit / 66 MHz 533
PCI-X 64 bit / 66 MHz 533
PCI-X 64 bit / 100 MHz 800
PCI-X 64 bit / 133 MHz 1066
Peak unidirectional Full Duplex Bandwidth
bandwidth
PCI-E x1 250 MBytes/s 500 Mbytes/s
PCI-E x2 500 MBytes/s 1 GBytes/s
PCI-E x4 1 GBytes/s 2 GBytes/s
PCI-E x6 2 GBytes/s 4 GBytes/s
PCI-E x16 4 GBytes/s 8 GBytes/s
PCI-E x32 8 GBytes/s 16 GBytes/s
PS:
1 上面的中文是自己翻译的如果有什么不合适的地方您还是看英文吧~!
2 Fv890、F6900、FE25K这几款机器在今天的sunsolve上还没看到有用PCI-E这种协议的接口的网卡、光纤卡或者I/O卡的,不过Enterprise M9000和T2000有用PCI-E的
[ 本帖最后由 maike_xiao 于 2008-5-8 17:36 编辑 ] |
|