The multiplier bug in inorder that was fixed a few months ago. -Soumyaroop
---------- Forwarded message ---------- From: Korey Sewell <[email protected]> Date: Wed, Sep 16, 2009 at 10:02 AM Subject: Re: Multiplier bug To: soumyaroop roy <[email protected]> Hmmm... GREAT CATCH.... I see the problem. The instruction should NOT leave stage 2 and complete the EndMultDiv request if the instruction has not been executed. Maybe the latency is not getting passed to the EndMultDiv event correctly. > 1. Stall the instruction from going past stage-2 till the > multiplication finishes by not setting the "completed" flag for the > resource request. However, that does not seem right. > That's right. The trick is, if you want a multicycle latency op, then you should schedule the resource request to finish X cycles later, not on the next cycle. Apologize again for no documentation. On the m5sim.org wiki page (http://m5sim.org/wiki/index.php/InOrder), I've got the TODO list for docs as: DOCUMENTATION TODO: (1) Pipeline Stages -->First Stage (2) Resources (3) Resource Pool (4) Pipeline Definition (5) Instruction Schedules Anything else pertinent that you think needs to be included to help understand? You can add it to the wiki TODO or just let me know. > > 2. Check at stage 4 from within the UseDefUnit if the result of the > instruction is ready or not by using one of the > isExecuted()/isCompleted()/isResultReady() accesors. This *should* be happening in the mult_div_unit.cc file. Cant be setting to "completed" if it hasnt executed! > > I have not used the stageTracing yet. I am not sure if it will be of > any further help anymore. Looks like you've identified it. > > Also, it appears (from pipeline_traits.cc) > that register read and issue to the arithmetic functional units take > place during the same cycle, like the MIPS processor. Is that correct? Yes. I made the model extensible though so that you can change it simply by editing that function. Hopefully people find that useful :) -- - Korey -- Soumyaroop Roy Ph.D. Candidate Department of Computer Science and Engineering University of South Florida, Tampa http://www.csee.usf.edu/~sroy _______________________________________________ m5-dev mailing list [email protected] http://m5sim.org/mailman/listinfo/m5-dev
