Question 1

You are tasked with setting up an HPC cluster using MPI over InfiniBand. As part of the setup, you need to ensure optimal data transfer performance between nodes. Which of the following is the most critical MPI feature for optimizing communication over InfiniBand in this context?

Options :

A : TCP/IP Communication

B : Blocking Send/Receive Operations

C : RDMA (Remote Direct Memory Access) Support

D : Shared Memory Communication (SHM)

Answer: C

Question 2

A financial services company is using RDMA over InfiniBand to accelerate the processing of real-time market data between servers. The application employs zero-copy techniques to avoid unnecessary data copies during communication. However, after switching to this configuration, the company observes that CPU utilization is still relatively high during data transfers, and performance gains are less than expected. What could be the most likely reason for the suboptimal performance?

Options :

A : Zero-copy requires additional software-based data serialization, which increases CPU overhead

B : The InfiniBand adapters are not using DMA (Direct Memory Access) for data transfers

C : The application is not properly registering memory regions for RDMA operations.

D : The zero-copy mechanism only applies to small data transfers, not to larger ones

Answer: C

Question 3

A financial services company is using RDMA over InfiniBand to accelerate the processing of real-time market data between servers. The application employs zero-copy techniques to avoid unnecessary data copies during communication. However, after switching to this configuration, the company observes that CPU utilization is still relatively high during data transfers, and performance gains are less than expected. What could be the most likely reason for the suboptimal performance?

Options :

A : Zero-copy requires additional software-based data serialization, which increases CPU overhead

B : The InfiniBand adapters are not using DMA (Direct Memory Access) for data transfers

C : The application is not properly registering memory regions for RDMA operations.

D : The zero-copy mechanism only applies to small data transfers, not to larger ones

Answer: C

Question 4

Which of the following best describes how RDMA (Remote Direct Memory Access) operations work within the InfiniBand protocol stack?

Options :

A : RDMA bypasses the CPU and operating system on the data path, allowing data to be directly transferred between the memory of two systems, reducing CPU overhead and improving data throughput.

B : RDMA allows memory access directly from one host’s CPU to another host-s memory without any involvement of the memory controller, reducing latency.

C : RDMA only works over the physical layer of the InfiniBand stack and requires additional middleware to handle data transfer at the transport layer.

D : RDMA requires the intervention of the OS kernel in both the sending and receiving systems, as it relies on kernel space memory buffers for transferring data between nodes.

Answer: A

Question 5

In InfiniBand, Virtual Lanes (VLs) are used to provide logical isolation of traffic within a single physical connection. What is the maximum number of Virtual Lanes supported by the InfiniBand standard, and what is their primary purpose?

Options :

A : 4 Virtual Lanes, used for low-latency traffic

B : 8 Virtual Lanes, used for data traffic prioritization only

C : 16 Virtual Lanes, with all used for data transmission

D : 15 Virtual Lanes, with one reserved for management traffic

Answer: D

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