Sane FireSim Default Target Freqs #836
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alonamid
requested review from
abejgonzalez,
jerryz123,
davidbiancolin and
sagark
jerryz123
reviewed
Mar 26, 2021
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I think the new configs should be: |
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While I'd love to see the pbus running a slower frequency than the sbus, unless there have been some recent changes in RC, that design point probably won't function correctly without further modification. IIRC RTC handling expects that SBUS and PBUS are running at the same freq. |
jerryz123
reviewed
Mar 29, 2021
| // Crossing specifications | ||
| new chipyard.config.WithCbusToPbusCrossingType(AsynchronousCrossing()) ++ // Add Async crossing between PBUS and CBUS | ||
| new chipyard.config.WithSbusToMbusCrossingType(AsynchronousCrossing()) ++ // Add Async crossings between backside of L2 and MBUS | ||
| new freechips.rocketchip.subsystem.WithAsynchronousRocketTiles(4,4) ++ // Add Async crossings between RocketTile and uncore |
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Am i mistaken, but weren't these rational earlier in the PR? They definitely should be.
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Related issue: N/A
Type of change: other enhancement
Impact: rtl change
Release Notes
Update FireSim default frequencies for better tile/system/memory ratios.
This PR changes the default FireSim target tile frequency from 3.2 GHz to 2 GHz (with a memory bus of 1 GHz), because 3.2 GHz generates an unrealistic Tile/Memory cycles ratio.
The default configs are also updated with a slower system bus (1 GHz).
The PR also adds two additional packaged config tweaks which are representative of High-Perf (Legacy) target configs, and test-chip target configs (1 GHz tile instead of 2 GHz).