Lecture 21 - HPC

What is a computer?

An electronic device that stores and processes digital info and follows programmed logic and instruction set.

What are the 5 components of a computer system?

CPU, memory, control unit, and I/O units.

What is the CPU (Central Processing Unit)?

Circuitry that carries out instructions of a computer program by using arithmetic, logical, and controlling I/O operations.

What controls the speed of the CPU?

The system clock.

What does the system clock do?

Generates electronic pulses at regular intervals to coordinate CPU activities, ensuring even the slowest operation can finish.

How is the performance of a CPU measured?

In clock speed (in GHz) and FLOPS (floating point operations per second).

What does FLOPS tell us?

How fast a single computation can be done by the CPU.

What does clock speed indicate?

How many instructions are performed per second by the CPU.

What is the thermal brick wall?

The clock-rate reached an upper limit because more cooling power is required.

Why do we need more cooling power for CPUs?

Higher CPU speed results in a higher clock rate, leading to faster electric current that generates more heat and lowers signal-to-noise ratio.

What is the current thermal brick wall for CPU speeds?

Hard to get above 4.0 GHz.

What are memory modules?

Any physical device capable of storing information for immediate use.

What is parallel computing?

Computation where many calculations are carried out simultaneously by breaking a big problem into smaller ones and solving them concurrently.

What is computational gain?

Serial time divided by parallel time.

What is parallel efficiency?

Computational gain divided by the number of processors.

What is serial computing?

A single processor running the computer program.

What is shared memory parallelism (OpenMP)?

Multiple processors or threads working on different parts of the program, sharing memory but sometimes competing for resources.

What is distributed parallelism (Message Passing Interface)?

Multiple processors working separately without having to contend with resources.

What is a supercomputer?

A computer cluster made of nodes (connected computers) that work together as a single system.

What is an OS?

Operating system is software closest to the computer hardware that manages all hardware and software, abstracting hardware from user programs.

What is SSH?

Secure Shell is a cryptographic network protocol for operating network services over an unsecured network, using encryption to secure connections between client and server.

What are the statistics of the Midway3 compute nodes?

192GB of memory, 100Gbps network, 24 cores, 3 GHz base frequency.

What is the storage of Midway3?

2.2 PB.

What is the shell?

Text-based terminal that takes in keyboard input and outputs text.

What is SLURM?

Workload manager that schedules jobs and manages resources between multiple users.

What are the 3 V's of big data?

Volume of data, Velocity of data transfers, Variety of types of data.

What is structured data?

Data that is formatted to be easily used with other databases.

What are examples of structured data?

Databases, JSON, HTML, CSV, etc.

What is unstructured data?

Data that is not structured, such as web pages, documents, pdfs, emails, media, sensor data.

What are the challenges of unstructured data?

They must be cleaned, outliers removed, pre-processed, edited, scraped, integrated, prepared, and analyzed.

What are the 4 rules of data trust?

Not all data is trustworthy, not all trustworthy data is correct, untrustworthy data is not always incorrect, even if data is correct, the answer may be wrong.

Why is data visualization necessary?

It helps create meaningful interpretations of results.