# Presentation: 211959

## Comprehensive Scientific Support 

**Of Large Scale Parallel Computation**
**David Skinner, NERSC**

## Overview

**What is NERSC? An insider’s view. **
**What is Comprehensive Scientific Support?**
**Summary of INCITE 2004**

## NERSC@LBL

- Focus on service to science projects
- Identification of research compute needs
- Experience with real scientific applications

- New tools and solutions
- Rapid introduction of new technology
- Perspectives on emerging architectures

- _Research provides_:

- _Facility provides_:

**Computational**
**Research **
**Division**

**Production**
**Computing**

## NERSC

**National Energy Research Scientific Computing Center**

** ****~2000 Users in ~400 projects**

** ****Serves all disciplines of the DOE Office of Science**

** ****Focus on large-scale computing**

## NERSC: Mission and Customers

**NERSC provides reliable computing infrastructure, HPC consultancy, and **
**accurate resource accounting to a wide spectrum of science areas. **

## Comprehensive Scientific Support

**Here’s the machine. What more do you need?**

## seaborg.nersc.gov

**seaborg.nersc.gov**

| Resource | Speed | Bytes |
| --- | --- | --- |
| Registers |     3 ns | 2560 B |
| L1 Cache |     5 ns |   32  KB |
| L2 Cache |   45 ns |     8  MB |
| Main Memory | 300 ns |   16  GB |
| Remote Memory |   19 us |     7  TB |
| GPFS |   10 ms |   50  TB |
| HPSS |      5 s |     9  PB |

- 380 x

- HPSS

- CSS0

- CSS1

-  Many Time Scales, Many Choices
-  NERSC Center is Focused on Scientific Productivity
-  Removing Bottlenecks Speeds Research

**IBM SP**

## Focus on Achieving Scientific Goals 

**Hardware and Software are only the start**
**Queue Policies, Allocation, Environment**
**User Training, Code analysis and Tuning**
**HW and SW testing, Reliability**
**An integrated approach enables rapid scientific impact. **
**Feedback from Researchers  is valued:**
**NUG (NERSC Users’ Group)**
**Collaborative contact with NERSC**

**Not just optimizing codes, NERSC optimizes the HPC process**

## Comprehensive Support

**HPC consultancy and visualization resources**
**A Breadth of Scientific and HPC Expertise**
**Systems Administration and Operation**
**High availability, RAS Expertise**
**Networking and Security**
**Secure access without jumping through hoops**

**So researchers can spend more time researching**
**For many projects NERSC is a hub for HPC services : data storage , visualization, CVS, web  **
**Quick Answers = Highly Productive Computing **

**Why**

**How**

## Examples of Comprehensive Support: Performance Tuning

** ****Analysis of Parallel Performance**
**Detailed view of how the code performs**
**Little effort by researcher**
** **
**Code Performance Tuning **
**Optimally tuned math libs**
**MPI Tuning**
**Scaling and Job structuring**
** **
**Parallel I/O strategies**
**Tuning for seaborg**
**Using optimal I/O libs**

## Examples of Comprehensive Support: Information Services

**An increasing number of information services are being offered through **_**[www.nersc.gov](http://www.nersc.gov/)**_
**Online documentation and tutorials **
**Machine Status / MOTD **
**Queue look, history, job performance records**
**Project level summaries via NIM**
**Send us your ideas for improvement.**
**Tell us what works for you. **

## Examples of Comprehensive Support: Information Services

**Login to **_[www.nersc.gov](http://www.nersc.gov/)_
**Batch job history and performance data are web accessible**

## The HPC Center: A Chemist’s View

**The HPC Center: A Chemist’s View**

- Reg_16

- Reg_64

- Reg_128

- Job S00509.280631.0

**Science Impact!**
- Code Performance Metrics
- Center Performance Feedback

- Queued
- Workload

- Computer

## INCITE 2004: Science Impact 

**Expanding Scientific Understanding  **
**A Quantum Mechanical understanding of how cells protect themselves from the photosynthetic engine.**
**Cosmological understanding of the distribution of atomic species generated by Supernovae.**
**Fundamental understanding of Turbulence and Mixing processes from astrophysical to microscopic scales.  **

## INCITE 2004: How we got there

**MPI tuning (15-40% overall improvments)**
**Scalability and  Load Balance**
**Advanced Math and MPI libraries**
**Parallel I/O **
**Optimizing concurrent writes**
**Implementing Parallel HDF **
**Misc. Programming**
**Batch “time remaining” routines**
**Threading and math library tests**
**Networked Data Transfer **
** ****from scp to hsi (0.5 ********70 MB/s) **

- HPC Support
- Yields Science
-  Productivity

## NERSC: Ready for New Challenges

**Emerging Software and Algorithms**
**Early testing of new HPC software**
**Performance analysis of new HPC applications**
**Emerging HPC Systems Technology **
**Parallel File Systems, Parallel I/O profiling **
**Emerging Architectures**
**“****Performance Characteristics of a Cosmology Package on Leading HPC Architectures”, HiPC 2004**
**“****Scientific Computations on Modern Parallel Vector Systems”, Supercomputing 2004**
**“****A Performance Evaluation of the Cray X1 for Scientific Applications”, VECPAR 2004**
**Partnerships to Improve HPC**
**BluePlanet / ViVA / Workload Analysis / PERC**

**INCITE 2005!**