IB读取，IB写入，OB读取和OB写的含义是什么.它们作为英特尔®PCM的输出，同时监视PCIe带宽 [英] What is the meaning of IB read, IB write, OB read and OB write. They came as output of Intel® PCM while monitoring PCIe bandwidth

问题描述

我正在尝试使用Intel®Performance Counter Monitor(PCM)工具测量NIC设备的PCIe带宽.但是，我无法理解它的输出.

I am trying to measure the PCIe bandwidth of NIC devices using Intel® Performance Counter Monitor (PCM) tools. But, I am not able to understand the output of it.

要测量PCIe带宽，我执行了二进制pcm-iio.该二进制文件有助于测量每个PCIe设备的监视器PCIe带宽.执行二进制文件后，我得到以下输出.

To measure the PCIe bandwidth, I executed the binary pcm-iio. This binary helps to measure the monitor PCIe bandwidth per PCIe device. After executing the binary I got the following output.

|IIO Stack 2 - PCIe1          |IB write|IB read|OB read|OB write|TLB Miss|VT-d L3 Miss|VT-d CTXT Miss|VT-d Lookup|
|_____________________________|________|_______|_______|________|________|____________|______________|___________|
| Part0 (1st x16/x8/x4)       |4498 M  |9003 M |   0   |3256 K  |   0    |   0        |   0          |   0       |
| Part1 (2nd x4)              |   0    |   0   |   0   |   0    |
| Part2 (2nd x8/3rd x4)       |   0    |   0   |   0   |   0    |
| Part3 (4th x4)              |   0    |   0   |   0   |   0    |
|_____________________________|________|_______|_______|________|________|____________|______________|___________|

我想了解IB读取，IB写入，OB读取和OB写入的含义.

I want to understand what is the meaning of IB read, IB write, OB read and OB write.

推荐答案

IB写入，是入站写入的缩写，是PCIe设备(在第一列中指定)请求发送的字节数.通过DMA写入主存储器. IB读取是PCIe设备请求通过DMA(直接内存访问")从主内存读取的字节数.无论是读取请求还是写入请求，都是将请求发送到套接字的设备(具体来说就是设备所连接的IIO堆栈).因此，从套接字的角度来看，这是入站流量.

IB write, short for inbound write, is the number of bytes that the PCIe device (specified in the first column) requested to write to main memory through DMA. IB read is the number of bytes that the PCIe device requested to read from main memory through DMA("Direct Memory Access"). Whether it's a read or write request, it's the device that is issuing the request to the socket (the IIO stack to which the device is connected, to be specific). So it's inbound traffic from the perspective of the socket.

这些指标是使用DATA_REQ_OF_CPU取消核心事件来衡量的.特别是，具有umask 0x1的事件表示一个4字节的入站写入请求，而具有umask 0x4的事件表示一个4字节的入站读取请求.

These metrics are measured using the DATA_REQ_OF_CPU uncore event. In particular, the event with umask 0x1 represents a 4-byte inbound write request and the event with umask 0x4 represents a 4-byte inbound read request.

OB写，是出站写的缩写，是处理器套接字请求通过MMIO(内存映射的I/O")写入PCIe设备的字节数. OB读取是处理器插槽请求通过MMIO从PCIe设备读取的字节数.

OB write, short for outbound write, is the number of bytes that the processor socket requested to write to the PCIe device through MMIO("Memory-mapped I/O"). OB read is the number of bytes that the processor socket requested to read from the PCIe device through MMIO.

除了使用DATA_REQ_BY_CPU uncore事件之外，这些度量的度量方式与入站度量的度量方式相似.

These metrics are measured similarly to the inbound ones, except that the DATA_REQ_BY_CPU uncore event is used instead.

在较旧的pcm-iio版本中，使用了完整形式的IB和OB.

In older versions of pcm-iio, the full form of IB and OB were used.

值得注意的是，DATA_REQ_OF_CPU不是衡量内存带宽，而是衡量连接到每个IIO堆栈的每个设备的I/O带宽.

It's worth noting that DATA_REQ_OF_CPU doesn't measure memory bandwidth, but rather I/O bandwidth for each device that is connected to each IIO stack.

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