Posted: 15 Jun 2017 | 13:41
We are entering the fourth year of the Intel Parallel Computing Centre (IPCC). This collaboration on code porting and optimisation has focussed on improving the performance of scientific applications on Intel hardware, specifically its Xeon and Xeon Phi processors.
Posted: 11 May 2017 | 00:06
As part of the ARCHER Knights Landing (KNL) processor testbed, we have produced and collected a set of benchmark reports on the performance of various scientific applications on the system. This has involved the ARCHER CSE team, EPCC's Intel Parallel Computing Center (IPCC) team, and various users of the system all benchmarking and documenting the performance they have experienced.
Posted: 10 Mar 2017 | 13:54
Thread and process binding
Note, this post was updated on the 23rd March 2017 to include how to bind threads correctly on Cray systems (aprun -cc rather than taskset)
Making sure threads and processes are correctly placed, or bound, on cores or processors is essential to ensure good performance for a range of parallel applications.
This is not a new topic, and has been covered well by others before, ie http://www.glennklockwood.com/hpc-howtos/process-affinity.html. Generally this is just handled for you; if you're running an MPI program then your mpirun/mpiexec/aprun job launcher will do sensible process binding to cores.
Posted: 30 Aug 2016 | 12:22
Knights Landing MPI performance
Following on from our recent post on early experiences with KNL performance, we have been looking at MPI performance on Intel's latest many-core processor.
The MPI performance on the first generation of Xeon Phi processor (KNC) was one of the reasons that some of the applications we ported to KNC had poor performance. Figures 1 and 2 show the latency and bandwidth of an MPI ping-pong benchmark running on a single KNC and on a 2x8-core IvyBridge node.
Posted: 20 Jul 2015 | 17:12
Experiences of porting and optimising code for Xeon Phi processors
EPCC is jointly organising a symposium at the ParCo conference on experiences from those working on porting and optimising codes for this architecture about the challenges and successes they have experienced when working with the Xeon Phi, and how these also apply to standard parallel computing hardware.
Posted: 15 Jul 2015 | 15:06
Discussions on computing
This one-week academy is designed to give PhD students some of the skills they need to undertake the range of computational simulations and data analysis tasks that their work requires.
Posted: 21 Jun 2015 | 20:02
The final analysis and future plans
A week ago we finished our 5 days of intensive work optimising CP2K (and to a lesser extent GS2) for Xeon Phi processors. As discussed in previous blog posts (Day4, Day3, Day2, Day1), this was done in conjunction with research engineers from Colfax, and built on the previous year's work on these codes by EPCC staff through the Intel-funded IPCC project.
Posted: 12 Jun 2015 | 15:41
MPI and vectorisation: Two ends of the optimisation spectrum
Day four of this week of intensive work optimising codes for Xeon Phi saw a range of work. The majority of the effort focussed on the vectorisation performance of CP2K and GS2; looking at the low level details of the computationally-intensive parts of these codes and seeing whether the compiler is producing vectorised codes, and if not is there anything that can be done to make the code vectorise.
Posted: 11 Jun 2015 | 16:01
Moving from OpenMP to vectorisation and MPI
Reality hit home a bit on the third day of our intensive week working with Colfax to optimise codes for the Xeon Phi.
After further implementation and analysis work it appears that the removal of the allocation and deallocation calls from some of the low level routines in CP2K will improve the OpenMP performance on Xeon and Xeon Phi, but only because there is an issue with the Intel compiler that is causing poor performance. The optimisation can see a reduction in runtime of around 20-30% for the OpenMP code, but only with versions 15 and 16 of the Intel compiler, on v14 there is a much smaller performance improvement.
Posted: 10 Jun 2015 | 00:08
Day 2: profiling and the start of optimising
After a first day spent getting codes set up and systems running, we got into the profiling of CP2K in anger today and have made some good progress.