Using Kure and Topsail

1. Using Kure and Topsail Mark Reed Grant Murphy Charles Davis ITS Research Computing

2. Outline • Compute Clusters • Topsail • Kure • Logging In • File Spaces • User Environment and Applications, Compiling • Job Management

3. Logistics • Course Format • Lab Exercises • Breaks • UNC Research Computing • http://its.unc.edu/research • Getting started Topsail page • http://help.unc.edu/6214 • Getting started Kure page • http://help.unc.edu/ccm3_015682

4. What is a compute cluster?What exactly is Topsail? Kure?

5. What is a compute cluster? Some Typical Components • Compute Nodes • Interconnect • Shared File System • Software • Operating System (OS) • Job Scheduler/Manager • Mass Storage

6. Compute Cluster Advantages • fast interconnect, tightly coupled • aggregated compute resources • large (scratch) file spaces • installed software base • scheduling and job management • high availability • data backup

7. Initial Topsail Cluster • Initially: 1040 CPU Dell Linux Cluster • 520 dual socket, single core nodes • Infiniband interconnect • Intended for capability research • Housed in ITS Franklin machine room • Fast and efficient for large computational jobs

8. Topsail Upgrade 1 • Topsail upgraded to 4,160 CPU • replaced blades with dual socket, quad core • Intel Xeon 5345 (Clovertown) Processors • Quad-Core with 8 CPU/node • Increased number of processors, but decreased individual processor speed (was 3.6 GHz, now 2.33) • Decreased energy usage and necessary resources for cooling system • Summary: slower clock speed, better memory bandwidth, less heat, quadrupled the core count • Benchmarks tend to run at the same speed per core • Topsail shows a net ~4X improvement • Of course, this number is VERY application dependent

9. Topsail – Upgraded blades • 52 Chassis: Basis of node names • Each holds 10 blades -> 520 blades total • Nodes = cmp-chassis#-blade# • Old Compute Blades: Dell PowerEdge 1855 • 2 Single core Intel Xeon EMT64T 3.6 GHZ procs • 800 Mhz FSB • 2MB L2 Cache per socket • Intel NetBurst MicroArchitecture • New Compute Blades: Dell PowerEdge 1955 • 2 Quad core Intel 2.33 GHz procs • 1333 Mhz FSB • 4MB L2 Cache per socket • Intel Core 2 MicroArchitecture

10. Topsail Upgrade 2 • Most recent Topsail upgrade (Feb/Mar ‘09) • Refreshed much of the infrastructure • Improved IBRIX filesystem • Replaced and improved Infiniband cabling • Moved cluster to ITS-Manning building • Better cooling and UPS

11. Top 500 History • Top 500 lists comes out twice a year • ISC conference in June • SC conference in Nov • Topsail debuted at 74 in June 2006 • Peaked at 25 in June 2007 • Still in the Top 500

12. Current Topsail Architecture • Login node: 8 CPU @ 2.3 GHz Intel EM64T, 12 GB memory • Compute nodes:4,160 CPU @ 2.3 GHz Intel EM64T, 12 GB memory • Shared disk:39TB IBRIX Parallel File System • Interconnect: Infiniband 4x SDR • 64bit Linux Operating System

13. Multi-Core Computing • Processor Structure on Topsail • 500+ nodes • 2 sockets/node • 1 processor/socket • 4 cores/processor (Quad-core) • 8 cores/node • http://www.tomshardware.com/2006/12/06/quad-core-xeon-clovertown-rolls-into-dp-servers/page3.html

14. Multi-Core Computing • The trend in High Performance Computing is towards multi-core or many core computing. • More cores at slower clock speeds for less heat • Now, dual and quad core processors are becoming common. • Soon 64+ core processors will be common • And these may be heterogeneous!

15. The Heat Problem Taken From: Jack Dongarra, UT

16. More Parallelism Taken From: Jack Dongarra, UT

17. Infiniband Connections • Connection comes in single (SDR), double (DDR), and quad data rates (QDR). • Topsail is SDR. • Single data rate is 2.5 Gbit/s in each direction per link. • Links can be aggregated - 1x, 4x, 12x. • Topsail is 4x. • Links use 8B/10B encoding —10 bits carry 8 bits of data — useful data transmission rate is four-fifths the raw rate. Thus single, double, and quad data rates carry 2, 4, or 8 Gbit/s respectively. • Data rate for Topsail is 8 GB/s (4x SDR).

18. Topsail Network Topology

19. Infiniband Benchmarks • Point-to-point (PTP) intranode communication on Topsail for various MPI send types • Peak bandwidth: • 1288 MB/s • Minimum Latency (1-way): • 3.6 ms

20. Infiniband Benchmarks • Scaled aggregate bandwidth for MPI Broadcast on Topsail • Note good scaling throughout the tested range (from 24-1536 cores)

21. Kure • The newest, “latest and greatest” compute cluster in RC • Named after the beach in North Carolina • It’s pronounced like the Nobel prize winning physicist and chemist, Madame Curie

22. Kure Compute Cluster • Heterogeneous Research Cluster • Hewlett Packard Blades • 79 Compute Nodes, mostly • Xeon 5560 2.8 GHz • Nehalem Microarchitecture • Dual socket, quad core • 48 GB memory • over 600 cores • some higher memory nodes • Infiniband4x QDR • priority usage for patrons • Buy in is cheap • Storage • Scratch space same as emerald • No AFS home

23. Kure Cont. • The current configuration of Kure is mostly homogeneous but it will become increasingly heterogeneous as patrons and others add to it. • Most login nodes are 48 GB but there are currently four high memory nodes • 2 nodes each with 128 GB of memory • 2 nodes each with 96 GB of memory

24. Topsail/Kure Comparison Topsail Kure heterogeneous 600+ cores 2.8 Ghz cores, Intel Nehalem micorarch. 48 GB memory/node IB 4x QDR interconnect • homogeneous • 4000+ cores • 2.33 GHz cores, Intel Core microarch. • 12 GB memory/node • IB 4x SDR interconnect

25. Login to Topsail/Kure • Use ssh to connect: • sshtopsail.unc.edu • sshkure.unc.edu • SSH Secure Shell with Windows • see http://shareware.unc.edu/software.html • For use with X-Windows Display: • ssh –X topsail.unc.edu orssh –X kure.unc.edu • ssh –Y topsail.unc.edu orssh –Y kure.unc.edu • Off-campus users (i.e. domains outside of unc.edu) must use VPN connection

26. File Spaces

27. Topsail File Space • Home directories • /ifs1/home/<onyen> • anyone over 15 GB is not backed up • Scratch Space • /ifs1/scr/<onyen> • over 39 TB of scratch space • run jobs with large output in this space • Mass Storage • ~/ms

28. Kure File Space • Home directories • /nas02/home/<a>/<b>/<onyen> • a = first letter of onyen, b = second letter of onyen • hard limit of 15 GB • Scratch Space – still evolving • /nas – to be upgraded to 15 TB • /largefs – to be upgraded to 30 TB • run jobs with large output in these spaces • Mass Storage • ~/ms

29. Mass Storage • long term archival storage • access via ~/ms • looks like ordinary disk file system – data is actually stored on tape • “limitless” capacity • data is backed up • For storage only, not a work directory (i.e. don’t run jobs from here) • if you have many small files, use tar or zip to create a single file for better performance • Sign up for this service on onyen.unc.edu “To infinity … and beyond” - Buzz Lightyear

30. User Environment and Applications, Compiling Code Modules

31. Modules • The user environment is managed by modules • Modules modify the user environment by modifying and adding environment variables such as PATH or LD_LIBRARY_PATH • Typically you set these once and leave them • Note there are two module settings, one for your current environment and one to take affect on your next login (e.g. batch jobs running on compute nodes)

32. Common Module Commands • module avail • module avail apps • module help • module list • module add • module rm Login version • module initlist • module initadd • module initrm More on modules see http://help.unc.edu/CCM3_006660

33. Parallel Jobs with MPI • There are three implementations of the MPI standard installed: • mvapich • mvapich2 (currently only on topsail) • openmpi • Performance is similar for all three, all three run on the IB fabric. Mvapich is the default. Openmpi and mvapich2 have more the the MPI-2 features implemented.

34. Compiling MPI programs • Use the MPI wrappers to compile your program • mpicc, mpiCC, mpif90, mpif77 • the wrappers will find the appropriate include files and libraries and then invoke the actual compiler • for example, mpicc will invoke either gcc or icc depending upon which module you have loaded

35. Compiling on Topsail/Kure • Serial Programming • Intel Compiler Suite for Fortran77, Fortran90, C and C++, - Recommended by Research Computing • icc, icpc, ifort • GNU • gcc, g++, gfortran • Parallel Programming • MPI (see previous page) • OpenMP • Compiler tag: -openmp for Intel -fopenmp for GNU • Must set OMP_NUM_THREADS in submission script

36. Debugging - Totalview • If you are debugging code there is a powerful commercial debugger, totalview • See http://help.unc.edu/CCM3_021717 • parallel and serial code • Fortran/C/C++ • GUI for source level control • too many features to list!

37. Job Scheduling and Management LSF

38. What does a Job Scheduler and batch system do? Manage Resources • allocate user tasks to resource • monitor tasks • process control • manage input and output • report status, availability, etc • enforce usage policies

39. Job Scheduling Systems • Allocates compute nodes to job submissions based on user priority, requested resources, execution time, etc. • Many types of schedulers • Load Sharing Facility (LSF) – Used by Topsail/Kure • IBM LoadLeveler • Portable Batch System (PBS) • Sun Grid Engine (SGE)

40. LSF • All Research Computing clusters use LSF to do job scheduling and management • LSF (Load Sharing Facility) is a (licensed) product from Platform Computing • Fairly distribute compute nodes among users • enforce usage policies for established queues • most common queues: int, now, week, month • RC uses Fair Share scheduling, not first come, first served (FCFS) • LSF commands typically start with the letter b (as in batch), e.g. bsub, bqueues, bjobs, bhosts, … • see man pages for much more info!

41. Simplified view of LSF job dispatched to run on available host which satisfies job requirements Jobs Queued job_J job_F myjob job_7 Login Node job routed to queue bsub–n 64 –a mvapich–q week mpirunmyjob user logged in to login node submits job

42. Running Programs on Topsail • Upon ssh to Topsail/Kure, you are on the Login node. • Programs SHOULD NOT be run on Login node. • Submit programs to one of the many, many compute nodes. • Submit jobs using Load Sharing Facility (LSF) via the bsub command.

43. Common batch commands • bsub - submit jobs • bqueues – view info on defined queues • bqueues –l week • bkill – stop/cancel submitted job • bjobs – view submitted jobs • bjobs –u all • bhist – job history • bhist –l <jobID>

44. Common batch commands • bhosts – status and resources of hosts (nodes) • bpeek – display output of running job • Use man pages to get much more info! • man bjobs

45. Submitting Jobs: bsub Command Submit Jobs - bsub Run large jobs out of scratch space, smaller jobs can run out of your home space bsub [-bsub_opts] executable [-exec_opts] Common bsub options: –o <filename> –o out.%J -q <queue name> -q week -R “resource specification” -R “span[ptile=8]” -n <number of processes> used for parallel, MPI jobs -a <application specific esub> -a mvapich(used on MPI jobs)

46. Two methods to submit jobs: • bsub example: submit the executable job, myexe, to the week queue and redirect output to the file out.<jobID> (default is to mail output) • Method 1: Command Line • bsub –q week –o out.%Jmyexe • Method 2: Create a file (details to follow) called, for example, myexe.bsub, and then submit that file. Note the redirect symbol, < • bsub < myexe.bsub

47. Method 2 cont. • The file you submitted will contain all the bsub options you want in it, so for this example myexe.bsub will look like this #BSUB –q week #BSUB –o out.%J myexe • This is actually a shell script so the top line could be the normal #!/bin/csh, etc and you can run any commands you would like. • if this doesn’t mean anything to you then nevermind :)

48. Parallel Job example Batch Command Line Method • bsub –q week –o out.%J-n 64 -a mvapich mpirun myParallelExe Batch File Method • bsub < myexe.bsub • where myexe.bsub will look like this #BSUB –q week #BSUB –o out.%J #BSUB –a mvapich #BSUB –n 64 mpirunmyParallelExe

49. Some Topsail Queues • For access to the 512cpu queue the scalability must be demonstrated

50. Some Kure Queues Most users have a 32 job slots limit unless they have been granted extra slots. Queues are always subject to changeand probably will change as Kure production ramps up. Use the bqueues command to find the current status