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?
Objective Understand the performance characteristics of multimedia workloads Compare them against SPEC CPU 2000
Multimedia Workloads Codecs used include: mp3, aac, MPEG2(dvd), windows media(dvd, HD), and MPEG4 Examine multimedia playback and creation (decoding/encoding)
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
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
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
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
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
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
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
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
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%
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
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
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
Your consent to our cookies if you continue to use this website.