1. Multimedia Workloads versus SPEC Benchmarks Christopher Martinez, Mythri Pinnamaneni, and Eugene John University of Texas – San Antonio

2. Outline Motivation Multimedia Workloads Cycles Per Instruction Branch Prediction Cache Performance Conclusion

3. Motivation The common workloads for the home user now focus upon entertainment For the home user entertainment performance is the selling point There are many media benchmarks but can SPEC benchmarks give some insight to entertainment applications?

4. Objective Understand the performance characteristics of multimedia workloads Compare them against SPEC CPU 2000

5. Multimedia Workloads Codecs used include: mp3, aac, MPEG2(dvd), windows media(dvd, HD), and MPEG4 Examine multimedia playback and creation (decoding/encoding)

6. Multimedia Workloads Decoding MP3/AAC – iTunes, Winamp, RealPlayer Video – Windows Media Player Encoding MP3 – iTunes, Windows Media Player, RealPlayer AAC – iTunes, RealPlayer Video – Windows Encoder

7. Multimedia Workloads MP3 files used a bitrate of 128kbps AAC files used a bitrate of 128kbps Video files used presets from applications Video was a TV capture of a football game Audio encoding was done on Beethoven Symphonie Pastoraie Audio playback was done on Boulevard Of Broken Dreams by Greenday

8. Performance Performance based on common measurements: cycles per instruction (CPI), uops per instruction, branch prediction, cache hit rate Use on chip performance counters on the Pentium 4 processor Use Vtune to capture the on chip counters

9. CPI Our test were performed on a Pentium 4 which is capable of executing 6 micro operation per second (uops) Audio decoding CPI --- 1.85 - 3.55 Audio encoding CPI --- 1.40 - 2.11 Video decoding --- 1.96 - 2.56 Video encoding --- 1.82 and 2.08 Integer SPEC 2000 CPI --- 1.16 - 8.54 Floating SPEC 2000 CPI --- 4.72 – 8.31

10. CPI

11. uops Audio decoding uops --- 1.38 – 1.71 Audio encoding uops --- 1.30 – 1.41 Video decoding uops --- 1.28 – 1.43 Video encoding uops --- 1.29 – 1.31 SPEC 2000 integer uops --- 1.29 – 2.11 SPEC 2000 float uops --- 1.32 – 2.48

12. Branch Prediction SPEC benchmarks have a large percentage of branch instructions than media applications Audio decoding -- 12% branch instructions Audio encoding -- 7% branch instructions Video decoding & encoding -- 8% branch instructions SPEC -- 13% - 20% branch instructions

13. Branch Prediction Media and SPEC benchmark exhibit a high branch prediction rate Prediction rates of 94% and higher in most cases With media application there is a high correlation between misprediction and CPI

14. Branch Prediction

15. Cache Performance The Pentium 4 processor has two level cache 1 st level 16KB & 2 nd level 1MB Multimedia deals with data in a linear fashion Audio/Video must be played in order This sequential data should allow for high hit rates Since SPEC benchmark covers a wide application range not all benchmarks will resemble the media hit rates

16. 1 st Level Cache Performance For 1 st level cache hit rates the multimedia had hit rates of 93% and higher Half of the SPEC benchmarks had similar 1 st level hit rates Remainder of the SPEC benchmarks were considerable worst performance

17. 1 st Level Cache Performance

18. 2 nd Level Cache Performance For all multimedia application 2 nd level cache had a hit rate of 99.8% or greater Only 5 of the 14 SPEC benchmarks had similar 2 nd level hit rates Most of the remaining SPEC benchmarks had 98% or higher but 2 SPEC had 86%

19. 2 nd Level Cache Performance

20. Conclusion Audio and video have similar range in CPI, uops per instruction, and uops per cycle SPEC programs exhibit performance characteristics in a much larger range than media. i.e SPEC suites are very diverse

21. Conclusion Both audio and video are comparable to SPEC in 2 nd level cache performance Half of the SPEC benchmarks resemble audio and video in 1 st level cache SPEC benchmarks can give some insight into performance of media applications

22. CPI iTunes MP3/AAC Decode1.85 / 1.98 WMV DVD/HD Decode1.96 / 2.14 Video Encode Pass1/Pass22.02 / 1.82 RealPlayer MP3 Encode2.02 iTunes MP3 Encode2.07 gcc / crafty / praser1.81 / 1.81 / 1.86 bzip22.06 Encode WMP MP3/ Real AAC1.66 / 1.71 Encode iTunes AAC1.40 gzip/ vortex/ gap1.52 / 1.32 / 1.40

23. CPI Winamp MP3 Decode3.11 Real MP3 Decode3.55 vpr3.17 Twolf3.36 Winamp AAC decode2.43 MPEG22.38 MPEG42.59 Real AAC Decode2.82 eon2.53

24. uops uops/instr MP3 Decode RealPlayer & iTunes1.54 AAC Decode RealPlayer/iTunes1.57/1.61 vortex1.60 parser1.52 gap1.53 twolf1.56

25. uops Encode MP3 WMP/ Real/ iTunes1.49 / 1.38 / 1.41 Encode AAC Real / iTunes1.38 / 1.30 Winamp AAC Decode1.38 MPEG2 / MPEG4/ WMV DVD1.43 / 1.37 / 1.28 WMV HD / pass1 / pass21.31 / 1.31 / 1.29 gzip / mcf / vpr1.35 / 1.29 / 1.46 art / crafty / perlbmk1.32 / 1.31 / 1.48 bzip21.42

26. uops Besides just similar number of uops one can also look at the cycles to complete the uop Cycle/uopCPI iTunes AAC Encode1.081.40 gcc1.051.81 gzip1.131.52

27. uops Decode Real MP3/AAC2.30 / 1.80 Decode winamp MP3 / AAC1.80 / 1.76 vpr / twolf2.17 / 2.15 Decode iTunes AAC / MP31.23 / 1.20 parser / eon1.22 / 1.20 Pass1 / pass21.59 / 1.42 bzip21.44 Encode MP3 Real / iTunes1.47 / 1.47

28. Branch Prediction % of branches Prediction RateMispredict/Instr Winamp MP312.894.920.0065 Real MP39.4191.500.0080 iTunes MP311.7697.840.0025 Winamp AAC16.8596.880.0053 Real AAC13.0295.260.0060 iTunes AAC12.8198.160.0024 Audio Decoding

29. Branch Prediction % of branches Prediction RateMispredict/Instr WMP MP39.0896.960.0028 Real MP310.4295.860.0043 iTunes MP30.5394.870.0055 Real AAC7.7494.520.0043 iTunes AAC7.6895.360.0035 Audio Encoding

30. Branch Prediction % of branches Prediction RateMispredict/Instr MPEG2 (DVD)8.9192.930.0063 MPEG48.2896.760.0027 WMV DVD5.1295.860.0021 WMV HD9.8996.300.0018 WMV HD - Pass1 6.3194.690.0033 WMV HD - Pass2 9.2895.460.0042 Video

31. Branch Prediction gcc21.8496.910.0067 gzip19.1094.890.0097 mcf24.2595.780.0102 vortex21.2299.750.0005 vpr16.5792.860.0118 art14.2199.210.0011 equake11.0098.210.0020 parser20.8096.650.0074 crafty15.7694.200.0091 eon13.4597.120.0039 gap17.5198.570.0025 perlbmk21.1898.560.0031 bzip214.8394.350.0084 twolf16.4888.390.0019

32. Branch Prediction The high correlation between branch prediction and CPI can give improvement insight When new CPU enhancements show improvement in SPEC, a similar or higher gain will be observed in multimedia applications