PCIE有四种不同的规格，通过下图来了解下PCIE的其中2种规格
查看主板上的PCI插槽
# dmidecode | grep --color "PCI"
不同PCIe版本对应的传输速率如下：
传输速率为每秒传输量GT/s，而不是每秒位数Gbps，因为传输量包括不提供额外吞吐量的开销位；
比如PCIe 1.x和PCIe 2.x使用8b/10b编码方案，导致占用了20% （= 2/10）的原始信道带宽。
GT/s —— Giga transation per second （千兆传输/秒），即每一秒内传输的次数。重点在于描述物理层通信协议的速率属性，可以不和链路宽度等关联。
Gbps —— Giga Bits Per Second （千兆位/秒）。GT/s 与Gbps 之间不存在成比例的换算关系。
PCIe 吞吐量（可用带宽）计算方法：
吞吐量 = 传输速率 * 编码方案
例如：PCI-e2.0 协议支持 5.0 GT/s，即每一条Lane上支持每秒钟内传输5G个Bit；但这并不意味着 PCIe 2.0协议的每一条Lane支持 5Gbps 的速率。
为什么这么说呢？因为PCIe 2.0 的物理层协议中使用的是8b/10b的编码方案。 即每传输8个Bit，需要发送10个Bit；这多出的2个Bit并不是对上层有意义的信息。
那么，PCIe 2.0协议的每一条Lane支持 5 * 8 / 10 = 4 Gbps = 500 MB/s 的速率。
以一个PCIe 2.0 x8的通道为例，x8的可用带宽为 4 * 8 = 32 Gbps = 4 GB/s。
PCI-e3.0 协议支持 8.0 GT/s, 即每一条Lane 上支持每秒钟内传输 8G个Bit。
而PCIe 3.0 的物理层协议中使用的是 128b/130b 的编码方案。 即每传输128个Bit，需要发送130个Bit。
那么， PCIe 3.0协议的每一条Lane支持 8 * 128 / 130 = 7.877 Gbps = 984.6 MB/s 的速率。
一个PCIe 3.0 x16的通道，x16 的可用带宽为 7.877 * 16 = 126.031 Gbps = 15.754 GB/s。
在 Linux 下要如何得知 PCI-E Bus 使用的是 Gen(Generation) 1 還是 Gen2 還是新一代的 Gen 3 雖然使用
#lspci 只要可以看到目前系統所有的裝置.但是好像看不到 PCI-E Bus 所採用的是哪一代的 PCI-E.
root@XXX# lspci 00:00.0 Host bridge: Intel Corporation Haswell DRAM Controller (rev 06) 00:01.0 PCI bridge: Intel Corporation Haswell PCI Express x16 Controller (rev 06) 00:01.1 PCI bridge: Intel Corporation Haswell PCI Express x8 Controller (rev 06) 00:02.0 VGA compatible controller: Intel Corporation Haswell Integrated Graphics Controller (rev 06) 00:03.0 Audio device: Intel Corporation Haswell HD Audio Controller (rev 06) 00:14.0 USB controller: Intel Corporation Lynx Point USB xHCI Host Controller (rev 05) 00:16.0 Communication controller: Intel Corporation Lynx Point MEI Controller #1 (rev 04) 00:1a.0 USB controller: Intel Corporation Lynx Point USB Enhanced Host Controller #2 (rev 05) 00:1c.0 PCI bridge: Intel Corporation Lynx Point PCI Express Root Port #1 (rev d5) 00:1c.4 PCI bridge: Intel Corporation Lynx Point PCI Express Root Port #5 (rev d5) 00:1c.5 PCI bridge: Intel Corporation Lynx Point PCI Express Root Port #6 (rev d5) 00:1d.0 USB controller: Intel Corporation Lynx Point USB Enhanced Host Controller #1 (rev 05) 00:1f.0 ISA bridge: Intel Corporation Lynx Point LPC Controller (rev 05) 00:1f.2 IDE interface: Intel Corporation Lynx Point 4-port SATA Controller 1 [IDE mode] (rev 05) 00:1f.3 SMBus: Intel Corporation Lynx Point SMBus Controller (rev 05) 00:1f.6 Signal processing controller: Intel Corporation Lynx Point Thermal Management Controller (rev 05) 01:00.0 PCI bridge: PLX Technology, Inc. Unknown device 8724 (rev ca) 02:01.0 PCI bridge: PLX Technology, Inc. Unknown device 8724 (rev ca) 02:02.0 PCI bridge: PLX Technology, Inc. Unknown device 8724 (rev ca) 02:08.0 PCI bridge: PLX Technology, Inc. Unknown device 8724 (rev ca) 02:09.0 PCI bridge: PLX Technology, Inc. Unknown device 8724 (rev ca) 03:00.0 Ethernet controller: Intel Corporation I350 Gigabit Network Connection (rev 01) 03:00.1 Ethernet controller: Intel Corporation I350 Gigabit Network Connection (rev 01) 03:00.2 Ethernet controller: Intel Corporation I350 Gigabit Network Connection (rev 01) 03:00.3 Ethernet controller: Intel Corporation I350 Gigabit Network Connection (rev 01) 04:00.0 Ethernet controller: Intel Corporation I350 Gigabit Network Connection (rev 01) 04:00.1 Ethernet controller: Intel Corporation I350 Gigabit Network Connection (rev 01) 04:00.2 Ethernet controller: Intel Corporation I350 Gigabit Network Connection (rev 01) 04:00.3 Ethernet controller: Intel Corporation I350 Gigabit Network Connection (rev 01) 06:00.0 Ethernet controller: Intel Corporation 82599EB 10-Gigabit SFI/SFP+ Network Connection (rev 01) 06:00.1 Ethernet controller: Intel Corporation 82599EB 10-Gigabit SFI/SFP+ Network Connection (rev 01) 07:00.0 PCI bridge: PLX Technology, Inc. PEX 8732 32-lane, 8-Port PCI Express Gen 3 (8.0 GT/s) Switch (rev ca) 08:01.0 PCI bridge: PLX Technology, Inc. PEX 8732 32-lane, 8-Port PCI Express Gen 3 (8.0 GT/s) Switch (rev ca) 08:08.0 PCI bridge: PLX Technology, Inc. PEX 8732 32-lane, 8-Port PCI Express Gen 3 (8.0 GT/s) Switch (rev ca) 08:09.0 PCI bridge: PLX Technology, Inc. PEX 8732 32-lane, 8-Port PCI Express Gen 3 (8.0 GT/s) Switch (rev ca) 08:0a.0 PCI bridge: PLX Technology, Inc. PEX 8732 32-lane, 8-Port PCI Express Gen 3 (8.0 GT/s) Switch (rev ca) 09:00.0 Ethernet controller: Intel Corporation 82599EB 10-Gigabit SFI/SFP+ Network Connection (rev 01) 09:00.1 Ethernet controller: Intel Corporation 82599EB 10-Gigabit SFI/SFP+ Network Connection (rev 01) 0e:00.0 Ethernet controller: Intel Corporation I210 Gigabit Network Connection (rev 03) 0f:00.0 Ethernet controller: Intel Corporation I210 Gigabit Network Connection (rev 03) root@XXX#
root@XXX# lspci -tv -[0000:00]-+-00.0 Intel Corporation Haswell DRAM Controller +-01.0-[0000:01-06]----00.0-[0000:02-06]--+-01.0-[0000:03]--+-00.0 Intel Corporation I350 Gigabit Network Connection | | +-00.1 Intel Corporation I350 Gigabit Network Connection | | +-00.2 Intel Corporation I350 Gigabit Network Connection | | \-00.3 Intel Corporation I350 Gigabit Network Connection | +-02.0-[0000:04]--+-00.0 Intel Corporation I350 Gigabit Network Connection | | +-00.1 Intel Corporation I350 Gigabit Network Connection | | +-00.2 Intel Corporation I350 Gigabit Network Connection | | \-00.3 Intel Corporation I350 Gigabit Network Connection | +-08.0-[0000:05]-- | \-09.0-[0000:06]--+-00.0 Intel Corporation 82599EB 10-Gigabit SFI/SFP+ Network Connection | \-00.1 Intel Corporation 82599EB 10-Gigabit SFI/SFP+ Network Connection +-01.1-[0000:07-0c]----00.0-[0000:08-0c]--+-01.0-[0000:09]--+-00.0 Intel Corporation 82599EB 10-Gigabit SFI/SFP+ Network Connection | | \-00.1 Intel Corporation 82599EB 10-Gigabit SFI/SFP+ Network Connection | +-08.0-[0000:0a]-- | +-09.0-[0000:0b]-- | \-0a.0-[0000:0c]-- +-02.0 Intel Corporation Haswell Integrated Graphics Controller +-03.0 Intel Corporation Haswell HD Audio Controller +-14.0 Intel Corporation Lynx Point USB xHCI Host Controller +-16.0 Intel Corporation Lynx Point MEI Controller #1 +-1a.0 Intel Corporation Lynx Point USB Enhanced Host Controller #2 +-1c.0-[0000:0d]-- +-1c.4-[0000:0e]----00.0 Intel Corporation I210 Gigabit Network Connection +-1c.5-[0000:0f]----00.0 Intel Corporation I210 Gigabit Network Connection +-1d.0 Intel Corporation Lynx Point USB Enhanced Host Controller #1 +-1f.0 Intel Corporation Lynx Point LPC Controller +-1f.2 Intel Corporation Lynx Point 4-port SATA Controller 1 [IDE mode] +-1f.3 Intel Corporation Lynx Point SMBus Controller \-1f.6 Intel Corporation Lynx Point Thermal Management Controller root@XXX#
如果有裝置是 unknown 的,需要更新 /usr/local/share/pci.ids.gz 請參考更新方式 http://benjr.tw/node/88
先查询 Inetl 82599EB 网卡的识别号(bus:device.function)
root@XXX# lspci | grep --color 82599 06:00.0 Ethernet controller: Intel Corporation 82599EB 10-Gigabit SFI/SFP+ Network Connection (rev 01) 06:00.1 Ethernet controller: Intel Corporation 82599EB 10-Gigabit SFI/SFP+ Network Connection (rev 01) 09:00.0 Ethernet controller: Intel Corporation 82599EB 10-Gigabit SFI/SFP+ Network Connection (rev 01) 09:00.1 Ethernet controller: Intel Corporation 82599EB 10-Gigabit SFI/SFP+ Network Connection (rev 01) root@XXX#
在 PCI 的装置使用三个编号用来当作识别值,个别为 1. "汇流排(bus number)", 2. "装置(device number) 以及 3. "功能(function number)".
所以刚刚的 06:00.0 就是 bus number = 06 ,device number = 00 function = 0 .
这3个编号会组合成一个 16-bits 的识别码,
汇流排(bus number) 8bits 2^8 至多可连接 256 个汇流排(0 to ff),
装置(device number) 5bits 2^5 至多可接 32 种装置(0 to 1f) 以及
功能(function number) 3bits 2^3 至多每种装置可有 8 项功能(0 to 7).
关于更多 #lspci 的资讯请参考 http://benjr.tw/node/543
然后查看vendor id和device id
root@XXX# lspci -n | grep -i 06:00.0 06:00.0 0200: 8086:10fb (rev 01) root@XXX#
Linux 使用 Class ID + Vendor ID + Device ID 來代表裝置,如剛剛的 0200: 8086:10fb 所代表裝置名稱為 (Class ID = 0200 , Vendor ID = 8086, Device ID = 10fb)
最后查看指定PCI设备的带宽
root@XXX# lspci -n -d 8086:10fb -vvv | grep --color Width LnkCap: Port #9, Speed 5GT/s, Width x8, ASPM L0s, Latency L0 <1us, L1 <8us LnkSta: Speed 5GT/s, Width x8, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt- LnkCap: Port #9, Speed 5GT/s, Width x8, ASPM L0s, Latency L0 <1us, L1 <8us LnkSta: Speed 5GT/s, Width x8, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt- LnkCap: Port #1, Speed 5GT/s, Width x8, ASPM L0s, Latency L0 <1us, L1 <8us LnkSta: Speed 5GT/s, Width x8, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt- LnkCap: Port #1, Speed 5GT/s, Width x8, ASPM L0s, Latency L0 <1us, L1 <8us LnkSta: Speed 5GT/s, Width x8, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt- root@XXX#
LnkSta : 目前系統所提供的速度 PCI-Express 2.0 ( 5GT/s )
LnkCap : 裝置目前所採用的速度.
LnkSta 和 LnkCap 這兩個速度有可能不一樣 , 典型情况下: 系統所提供的是 PCI Express 是 3.0 但裝置還是使用 2.0 的.
以上就是本次介绍的相关知识点，感谢大家的学习和对好代码网的支持。
