Verification regression consumes expensive compute resources and precious project time, so any speed-up has both a technical and business impact. As announced July 17, Fujitsu was able to improve both the compute resource and project time by using Cadence Incisive products and working closely with Cadence field resources to deploy them. Results: 1.5x faster per test, 3x faster regression overall, and 30x storage reduction. Wow.
The first step was to optimize each test. Fujitsu upgraded to the Incisive 12.1 release (shipped June 2012) and applied a feature called "zlib". This feature compresses the simulatable snapshot. The smaller executable is written faster, occupies less disk space, and loads faster. Together with the performance improvements available out-of-the-box with the 12.1 release, each test was able to run 1.5x faster, on average. The Cadence team expects further gains when Fujitsu moves to the latest 13.1 release.
The next step was to apply a technology called incremental elaboration. The technology allows one or more elaborated "objects" to be created and then linked prior to simulation. For an individual engineer, the technology means you can link the few blocks you change to the much larger subsystem or system without re-elaborating the unchanged code.
Fujitsu employed the technology in a slightly different use model. In regression, there is a matrix of tests and DUT configurations. In Fujitsu's case, there were 190 tests but only 24 unique Standard Delay Format (SDF) test scenarios. Before the incremental elaboration was applied, each test scenario was compiled and elaborated with each DUT configuration, resulting in 190 separate elaborations. When the incremental elaboration was applied, the 24 SDF primary elaborations were linked to the appropriate DUT. The resulting reduction in compute time for elaboration and storage for the snapshots was combined with the individual test improvements to yield 3x total regression time speed-up and 30x less disk storage.
The final step was automating this process. The single-elaboration approach is slower but is straightforward becasue each configuration is created new. Manually integrating the incremental "primaries" is challenging when there are 190 unique tests.
Fujitsu automated this process by applying the Incisive Enterprise Manager (IEM) in several ways. First, the IEM test runner was able to automatically build the appropriate incremental primaries and link them for each test run. Second, IEM was able to detect whether an individual test passed or failed, eliminating the "eye-ball" check of the log file or waveforms. Finally, IEM was able to aggregate the results back to a verification plan (vplan) to show overall project-level progress for the entire regression.
What does the future hold? Newer releases of Incisive Enterprise Simulator add more out-of-box performance improvements, add black-boxing features, and the ability to link multiple primaries which will make regression faster and make automation more important. Keeping pace, the Incisive Enterprise Manager adds new analysis features to better automate the overall process.
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=Adam Sherer, Incisive Product Management Director