The Department of Energy’s planned 200 petaflops Summit computer, which is currently being installed at Oak Ridge Leadership Computing Facility, is on track to be completed in early 2018 according to an OLCF presentation made last week at the HPCXXL meeting. There had been some speculation Summit might be running by SC17. Standing up such massive machines is typically a painstaking process.

OLCF researcher Wayne Joubert told the audience, “We now have all of the cabinets delivered to Oak Ridge and installed. They are empty cabinets – we are still waiting for the processor boards. [Work] on the fiber optic cables is partly done and in progress now. We hope in early 2018 to have the entire system delivered. We’ll start working on it [then], trying out our codes on it and driving to acceptance of the system later in 2018.”

Joubert’s talk (Evaluating functionality and performance of IBM Power8+ systems) highlighted a dedicated OpenPOWER day at the HPCXXL[i] summer meeting held in New York. HPCXXL is a user group for sites which have large installations of IBM or Lenovo equipment. The focus of the HPCXXL group is on large-scale scientific/technical computing using IBM or Lenovo hardware.

Joubert reviewed work being done on the Summitdev machine – a one petaflop ‘prototype’ – in preparation for Summit. IBM (Power CPU) and Nvidia (P100 GPU) are key vendors on the project. Summitdev is an impressive computer on its own (specs below) that outperforms Titan in several areas. Titan was one of the first leadership computers to use heterogeneous (CPU plus GPU) architecture.

OLCF took delivery of Summitdev, a three cabinet 54-node IBM Minsky system, last October. Summitdev is primarily intended for code teams to prepare applications for Summit, a Power9 / Volta system that is among the pre-exascale machines DoE is funding on the path to exascale. Summit is expected to deliver 200 petaflops of double precision performance, and, based on Nvidia announcements, it will provide 3.2 exaflops of mixed precision performance for machine learning applications. “We expect Summit to be the world’s most powerful machine learning system,” said Joubert.

The big difference between Summitdev and Summit – besides sheer size – is use of IBM’s newest processor, the Power9, which has been much anticipated. Summitdev uses IBM Power8+ chips introduced roughly a year ago as the core of IBM’s Minsky PowerAI platform (see HPCwire article, IBM Launches PowerAI Suite Optimized for its Highest Performing Server.) IBM’s high-end server (S822LC for HPC) with Power8+ and NVlink was one of the first systems to ship with Nvidia’s new P100 GPU.

Summitdev was delivered to OLCF last October, underwent the usual testing and was accepted in early December. Since then more work has been done around debugging and evaluating system software and application performance. Joubert’s update covered acceptance work and recent evaluations. Summit, in addition to the new Power9 CPU, will have Nvidia’s new Volta 100 GPU.

OLCF director Arthur “Buddy” Bland declined to say whether OLCF had been working with early Power9 silicon, but said he didn’t think transitioning from the Power8+ to Power9 would be a problem. He also confirmed the Summit rollout schedule.

“Our team does not expect the port from Power8 to Power9 to be difficult. We fully expect that codes will move over with little effort. Of course, as with any system modifications may be needed to take full advantage of the new features. The details of Power9 are still under NDA so I can’t really say any more at this time. As for the dates, we have been saying for a long time that we expect to have the machine installed in 2018 and put early users on in the second half of 2018,” said Bland.

Most Joubert’s talk covered the Summitdev performance testing. The problems encountered, he said were largely typical. There were a few early hardware problems. A wide variety of compilers (XL, PGI, GNU, LLVM) and libraries et. al. were tested. Interestingly, LLVM, perhaps because it is still new, had a couple of glitches.

Application performance was generally encouraging and in line with expectations. The OLCF team not only examined required CORAL apps but also a few other science applications that are heavily used.

You can see from the slide below that Summitdev is already surpassing Titan on select applications such as QMCPACK.

The OLCF update of the Summitdev/Summit project was just one of several IBM-centric presentations made at the OpenPOWER day. Here are links to a few other presentations:

Link to OLCF presentation video: https://www.youtube.com/watch?v=gb9yUI9H2mk

Link to OLCF presentation slides: https://ibm.ent.box.com/v/hpcxxlopenpowerdday2017/file/230502745769

Link to all HPCXXL presentations: https://ibm.ent.box.com/v/hpcxxlopenpowerdday2017

OpenPOWER YouTube channel: https://www.youtube.com/channel/UCYLtbUp0AH0ZAv5mNut1Kcg

[i] HPCXXL is a user group for sites which have large installations of IBM or Lenovo equipment. The focus of the HPCXXL group is on large-scale scientific/technical computing using IBM or Lenovo hardware. Some of the areas we cover are: Applications, Code Development Tools, Communications, Networking, Parallel I/O, Resource Management, System Administration, and Training. We address topics across a wide range of issues that are important to sustained multi-petascale scientific/technical computing on scaleable parallel machines.

The HPCXXL is a self-organized and self-supporting group. Members and affiliates are expected to participate actively in the HPCXXL meetings and activities and to cover their own costs for participating. HPCXXL meetings are open only to members and affiliates of the HPCXXL. HPCXXL member institutions must have an appropriate non-disclosure agreement in place with IBM and Lenovo, since at times both vendors disclose and discusses information of a confidential nature with the group. Beginning in 2018 the spring workshop will be co-located with the HPC Advisory Council Switzerland in Lugano without a vendor dedicated focus. The summer/autum workshop will be traditionally focused on IBM and their partners.