DI unit balanced port allocation fix #431
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FinnWilkinson
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jj16791,
JosephMoore25 and
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ABenC377
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JosephMoore25
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jj16791
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I do agree that performance needs to be a concern, but for me this could be a necessary case where the minor performance hit (if apparent) needs to be taken. Without this change, I don't think we are properly or accurately allocating to ports in a true balanced fashion. Having said that, if the performance hit is major, then a different solution should be looked into. |
FinnWilkinson
added
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…port allocation failure but instead cycling through all possible RSs.
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ABenC377
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jj16791
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@FinnWilkinson Could you open an issue detailing the performance issue that comes with this PR and the discussed high-level solution
JosephMoore25
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Currently, the dispatch issue unit will get one port allocation and if the attached Reservation station is full or has exhausted its dispatch rate for that cycle, the port will be unallocated and a stall will occur.
Given many instructions can have multiple ports to go to, we should be cycling through all legal ports and seeing if an instruction can be accepted into any of its reservation stations. This PR makes such a change and improves & balances the port / reservation station utilisation.