1. Hepmark project Evaluation of HEP worker nodes Michele Michelotto at pd.infn.it

2. CdS - Luglio 2008 michele michelotto - INFN PD2 Computing model Tier3 physics department    Desktop Germany Tier-1 UK France Italy CERN Tier 1 Japan CERN Tier 0 Tier-2 Lab a Uni a Lab c Uni n Lab m Lab b Uni b Uni y Uni x grid for a regional group USA BNL USA FNAL grid for a physics study group

3. CdS - Luglio 2008 michele michelotto - INFN PD3 Computing Needs Tape Storage: –Very Easy: events  Terabyte Disk Storage –Easy again: events  Terabyte –(1000x1000 or 1024x1024?) –RAID protected or raw size? Computing Power –Tricky: Event/sec? Sim or Reco? –MIPS, CernUnit, MHz, Spec, SI2K….

4. CdS - Luglio 2008 michele michelotto - INFN PD4 T1 + T2 cpu budget - LHC

5. CdS - Luglio 2008 michele michelotto - INFN PD5 FZK Measurement In 2001 SPEC with gcc was 80% of the average pubblished data In 2006 the gap was much wider

6. CdS - Luglio 2008 michele michelotto - INFN PD6 The SI2K inflaction The main problems with SI2000 in our community: it is not proportional to HEP codes performance (as it was) You can buy processors with huge SI2K number but with a smaller increase in real performances

7. CdS - Luglio 2008 michele michelotto - INFN PD7 Nominal SI vs real SI SI2K results for the last generation processor affected by inflation So CERN (and FZK) started to use a new currency: SI2K measured with “gcc”, the gnu C compiler and using two flavour of optimization –High tuning: gcc –O3 –funroll-loops– march=$ARCH –Low tuning: gcc –O2 –fPIC –pthread

8. CdS - Luglio 2008 michele michelotto - INFN PD8 Nominal SI vs real SI CERN Proposal: Use as site rating the “Real SI” obtained by SI measured with gcc-low and increased by 50% –Actually this make sense only for a short period of time and for the last generation of processor Run n copies in parallel –Where n is the number of cores in the worker node –To take in account the drop in performance of a multicore machine when fully loaded.

9. CdS - Luglio 2008 michele michelotto - INFN PD9 Too many SI2K Take as an example a worker node with two Intel Woodcrest dual core 5160 at 3.06 GHz SI2K nominal: 2929 – 3089 (min – max) SI2K sum on 4 cores: 11716 - 12536 SI2K gcc-low: 5523 SI2K gcc-high: 7034 SI2K gcc-low + 50%: 8284

10. CdS - Luglio 2008 michele michelotto - INFN PD10 Which is the better? I started to measure performances of HEP codes on several machines The goal was to find a “commercial mantained” benchmark to replace SI2K I compared HEP code with –SI2K pubblished results –SI2K measured with gcc and “CERN” tuning –SI2006 and SI2006 rate pubblished results –SI2006 and SI2006 with gcc4 (32 and 64 bit)

11. CdS - Luglio 2008 michele michelotto - INFN PD11 CMS sw SIM and Pythia CMS Montecarlo simulation (32bit) and Pythia (64bit) show the same performance once normalized Both Specint 2006 pubblished and Specint 2006 with gcc show the same behaviour SI2K pubbished does not match HEP sw SI2K cern better but not as good as SI2006

12. CdS - Luglio 2008 michele michelotto - INFN PD12 Babar TierA Results If you normalize by core and clock all new processors have the same performance Doubling the older generation cpu SI2006 matches this pattern (pubblished and gcc ratio constant) SI2000-cern better than SI2K nominal SI2000 clearly doesn’t work

13. CdS - Luglio 2008 michele michelotto - INFN PD13 Many gaps Easy to find SPEC pubblished result –But only for new machines Difficult to measure: –Not easy to have machine on loan from Server reseller or producer –Not easy to borrow machine from colleagues –Always for short periods of time –A SPEC run can last 15-20 hours Need a set of dedicated worker node to make SPEC and HEP application measurement

14. CdS - Luglio 2008 michele michelotto - INFN PD14 Cache In the 80’s the latency (3-10 clock time) Now latency is 1000s of clock time Importance of the cache architecture –1st level, 2nd level, 3rd level –Cache latency –Cache bandwidth –Shared or exclusive?

15. CdS - Luglio 2008 michele michelotto - INFN PD15 4 core processor

16. CdS - Luglio 2008 michele michelotto - INFN PD16 Intel 54xx

17. CdS - Luglio 2008 michele michelotto - INFN PD17 AMD 4core

18. CdS - Luglio 2008 michele michelotto - INFN PD18 Load transactional Performance don’t drop in the new 4core processor Clovertown drop wrt Harpwertown A dual core processor keeps only up to Load3

19. CdS - Luglio 2008 michele michelotto - INFN PD19 Perf/watt AMD Barcelona at 65nm Performance per watt similar to INTEL xeon at 45nm

20. CdS - Luglio 2008 michele michelotto - INFN PD20 Cache behaviour 54xx has lower latency even with bigger cache The 3 processors behave very differently in the 4MB e 64MB range If your (HEP) application works in this range you will see a big change of performance changing processor

21. CdS - Luglio 2008 michele michelotto - INFN PD21 Memory intel vs amd Access time very similar At 1GB (tipical footprint of HEP application) the new AMD behave better But the new are Xeon 54xx much better than the 53xx

22. CdS - Luglio 2008 michele michelotto - INFN PD22 Mem intel vs amd Who is faster? It depends on the block size On the red zones Intel is better. On the green zone AMD is better

23. CdS - Luglio 2008 michele michelotto - INFN PD23 Cache behaviour We need to study the behaviour of tipical HEP application –Simulation, event generation, Reconstruction, Analysis –To understand how to write more efficient application

24. CdS - Luglio 2008 michele michelotto - INFN PD24 Power issues Power consumption change from one processor to another – Clock, High-K dielectric, Active Power Managements, Clock throttling

25. CdS - Luglio 2008 michele michelotto - INFN PD25 Power consumption

26. CdS - Luglio 2008 michele michelotto - INFN PD26 An HEP data center Need to make measurement of Power usage for HEP application Example: a big Tier2 with 500 boxes needs 100kW –Like the whole CED of INFN Padova –About 800 MWh in one year –Energy cost 0.12 Euro per kWh  Energy bills of 100 kEuro/year –A 10% improvement on Power efficiency means 10 kEuro/year savings –And savings on the infrastructure (power distribution, UPS, Cooling)

27. CdS - Luglio 2008 michele michelotto - INFN PD27 Power meter Need a device to measure Voltage and Current And logging capabilities E.g. Fluke 1735

28. CdS - Luglio 2008 michele michelotto - INFN PD28 Financial request Need to buy a new worker node each time a new processor is released in the dual proc market segment –Only if significantly new features are presents –One or two each for INTEL and AMD per year –4 kEuro each (dual proc, 2GB/core, 1disk) –2 box to start with

29. CdS - Luglio 2008 michele michelotto - INFN PD29 Manpower Padova: –Michele Michelotto (Primo Tecnologo) 70% –Alberto Crescente (CTER) 30% –Roberto Ferrari (CTER) 30% Ferrara: –Alberto Gianoli (Primo Tecnologo): 20% Bologna: –Franco Brasolin (CTER): 20%

30. CdS - Luglio 2008 michele michelotto - INFN PD30 Milestone 2009 –Undestand SPEC 2006. Propose a new benchmark to replace SI2K –Measure the performance of the current architectures for Montecarlo SIM (evt/sec vs SPEC) 2009/2010 –Power performances 2010 –Cache profiling

31. CdS - Luglio 2008 michele michelotto - INFN PD31 Question?

32. CdS - Luglio 2008 michele michelotto - INFN PD32 Backup slides Backup Slides

33. CdS - Luglio 2008 michele michelotto - INFN PD33 SI2K frozen SI2K is the benchmark used up to now to measure the computing power of all the HEP experiments –Computing power requested by experiment –Computing power provided by a Tier-[0,1,2] SI2K is the nickname for SPEC CPU Int 2000 benchmark –Came after Spec89, Spec Int 92 and Spec Int 95 –Declared obsolete by SPEC in 2006 –Replaced by SPEC with CPU Int 2006

34. CdS - Luglio 2008 michele michelotto - INFN PD34 Transition problem Impossible to find SPEC Int 2000 pubblished results for the new processors (e.g. the not so new Clovertown 4-core) Impossible to find pubblished SPEC Int 2006 for old processor (before 2006) –E.g. Old P4 Xeon, P4, AMD 2xx You can’t convert from SI2000 to SI2006 but the ratio for x86 architecture is in the 137 – 172 range

35. CdS - Luglio 2008 michele michelotto - INFN PD35 Even more Actually all the gcc results in the previous slide are on i386 (32bit) if you would like to know how your code is running on 64 bit machine, you can measure Specint INT 2000 with gcc on x86_64. So the worker node with two Intel Woodcrest dual core 5160 at 3.06 GHz SI2K nominal: 2929 – 3089 (min – max) SI2K on 4 cores: 11716 - 12536 SI2K gcc-low: 6021 SI2K gcc-high: 6409 SI2K gcc-low + 50%: 9031

36. CdS - Luglio 2008 michele michelotto - INFN PD36 Atlas Here 100% is Xeon5160 Few results for SI2006+gcc but no diff from CMS and babar Few results also from SI2006 pubblished because of several old architectures SI2K+gcc not bad SI2K pubblished heavily overstimate new Xeon Atlas simulation normalized performs the same on the new intel “core” or amd “opteron” (like CMS, Babar)