1 / 11

HPC User Forum, April 2008 John Hesterberg

HPC OS Directions and Requirements. HPC User Forum, April 2008 John Hesterberg. Processor-rich environments. Today's max SGI system sizes: 1000s of cores per ccNUMA Single System Image (SSI) ‏ 2048 -> 4096 cores limited by Linux scalability 1000s of small SSI nodes per system 14336 cores

aswearingen
Download Presentation

HPC User Forum, April 2008 John Hesterberg

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. HPC OS Directions and Requirements HPC User Forum, April 2008 John Hesterberg

  2. Processor-rich environments • Today's max SGI system sizes: • 1000s of cores per ccNUMA Single System Image (SSI)‏ • 2048 -> 4096 cores • limited by Linux scalability • 1000s of small SSI nodes per system • 14336 cores • limited by cost • Mutli-core is another layer of NUMA! In one SSI: • threads in a core • cores in a cpu/socket • sockets on a numa (or bus) node • numa nodes in a SSI • latency/bandwidth between nodes • SSIs in a system

  3. Processor-rich environments • Job placement, scheduling continue to be critical, both within SSI and across SSIs • batch managers need to see topology • placement policies based on applications • within a node: • processor/cache/node affinity • cpusets • isolated cpus • across nodes: • synchronized scheduling

  4. Resiliancy requirements • all hardware is not created equal. :)‏ ... but all hardware will fail • tolerate as many failures as possible • memory in particular • diskless clusters eliminate one more failure component • this is an ongoing (and endless) effort • tight integration between software and hardware helps • as systems scale, node failures become a certainty • application based checkpoint/restart? • OS supported checkpoint/restart?

  5. The Power of Linux • Disruptive OS development process • >1000 developers, 186 known companies (2.6.24)‏ • https://www.linux-foundation.org/publications/linuxkerneldevelopment.php • That's just the kernel!!! • Code reviews and signoffs • Hard and controversial changes get reviewed and done right • Open Source Flexibility • Can be customized for HPC hardware • Can be on the cutting edge of research • Productized and supported • Same OS on laptop, desktop, clusters with 1000s of nodes, SSIs with 1000s of cores • No vendor lock-in.

  6. Virtualization • Microkernel approaches (e.g. Xen)‏ • hides hardware details :-( • how much memory do you want to waste? • how much cpu do you want to waste? • what about IO performance? • KVM more interesting for some problems • First domain runs directly on hardware • Additional domains for compatibility. • Rebooting • Can be better for clusters with dedicated nodes...compare boot times to job runtimes • No added runtime overhead • Provides clean image • Multiple boot images on disk or on server • Integrate into batch manager!

  7. Green Computing • hardware is helping and hurting... • laptop capabilities moving up • more and larger systems consuming more power • HPC challenge: save power w/o sacrificing performance • tickless OS • cpu frequency management • management of idle cpus, nodes, and systems

  8. Slide 8

  9. OS Noise Synchronization‏ Unsynchronized OS Noise → Wasted Cycles Process on: Wasted Cycles Wasted Cycles System Overhead Node 1 Node 2 Compute Cycles Wasted Cycles System Overhead Wasted Cycles Node 3 System Overhead Wasted Cycles Wasted Cycles Barrier Complete Process on: System Overhead Node 1 System Overhead Node 2 System Overhead Node 3 Synchronized OS Noise → Faster Results Time • OS system noise: CPU cycles stolen from a user application by the OS to do periodic or asynchronous work (monitoring, daemons, garbage collection, etc). • Management interface will allow users to select what gets synchronized • Huge performance boost on larger scales systems Slide 9

  10. Servers: One Size Doesn’t Fit All! Focus on Efficiency Focus on Innovation • Workflow Characteristics • Price-performance key • Little data sharing • Predictable Workloads • Non-interactive • Standard Modes • Mature Apps • Workflow Characteristics • Multi-Discipline • Data-Intensive • Mixed or Uncertain Workloads • Interactivity • Rapid development cycles Capability & Conceptual Computing Capacity & Compliant Computing Slide 10

  11. User Productivity Advantages of Large Global Shared Memory Freedom to arbitrarily scale problem size without decomposition or other rework Minimal penalty to fetch off-node data Ability to freely exploit Open MP and/or MPI in any combination or scale. Simplified code development and prototyping platform Freedom to experiment without the hindrance of cluster paradigms Unified parallel C translator in development Greatly simplified load balancing Simple to direct a task to any processor as all data is accessible

More Related