Hi Kazi, Matt's assumption is correct. Voltage does not affect the correctness of the model. You can see the scope of the voltage domain in src/sim/voltage_domain.cc Changing the voltage when the DVFS is enabled changes the clock frequency according to the perf levels that have been set. One can then use the information from these logs to get the total power consumed by the voltage-frequency domain using a separate power model.
Thanks, Srikant On Mon, Apr 3, 2023 at 8:20 PM Matt Sinclair <sincl...@cs.wisc.edu> wrote: > DVFS is not my area of expertise, so I’m not sure I can offer much useful > feedback here. My guess is you probably meant line 429 of what I see on > develop: > https://gem5.googlesource.com/public/gem5/+/refs/heads/develop/configs/example/apu_se.py#429 > ? > > > > Regardless, without more information it’s hard to say what is failing. > But I believe the voltage does not fundamentally affect the correctness of > the model – regardless of what model you set, it runs at the set frequency > and eventually completes. I **think** the voltage is more for the energy > modeling aspects. But Srikant (CC’d) knows a lot more about GPU DVFS in > gem5, so hopefully he can comment further. > > > > Matt > > > > *From:* Mejbaul Islam, Kazi M. <kmejbaulis...@ufl.edu> > *Sent:* Monday, April 3, 2023 10:04 PM > *To:* Matt Sinclair <sincl...@cs.wisc.edu>; gem5-users@gem5.org > *Cc:* Poremba, Matthew <matthew.pore...@amd.com>; srikan...@gmail.com > *Subject:* Re: How to change voltage and frequency of individual > ComputeUnit for GPU? > > > > Hi, > > > > Thank you so much, will definitely contribute if I can do that. On a > similar note, I have first tried to change voltage and frequency of shader > in gem5/configs/example/apu_se.py (line 412). The thing is, beyond a > certain range of GPU frequency, it crashes which makes sense. But if I put > gpu_voltage=0.0V it still works fine as it is (with same ticks and all). > Even I have changed CPUvoltage and gpu_voltage to 0.0V but it works which > is wired. Where may be the issue do you think? > > > > Regards, > > Kazi > ------------------------------ > > *From:* Matt Sinclair <sincl...@cs.wisc.edu> > *Sent:* Monday, April 3, 2023 5:00 PM > *To:* gem5-users@gem5.org <gem5-users@gem5.org> > *Cc:* Mejbaul Islam, Kazi M. <kmejbaulis...@ufl.edu>; Poremba, Matthew < > matthew.pore...@amd.com>; srikan...@gmail.com <srikan...@gmail.com> > *Subject:* Re: How to change voltage and frequency of individual > ComputeUnit for GPU? > > > > *[External Email]* > > Hi Kazi, > > > > Srikant (CC'd) previously added some support for things like this ( > https://gem5-review.googlesource.com/c/public/gem5/+/61589 > <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgem5-review.googlesource.com%2Fc%2Fpublic%2Fgem5%2F%2B%2F61589&data=05%7C01%7Ckmejbaulislam%40ufl.edu%7C48e15cbe38e348f945ef08db34866a8c%7C0d4da0f84a314d76ace60a62331e1b84%7C0%7C0%7C638161524140252353%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=8uZWWy6MRrTlYItcNhNpy4pijQZ2USNgDp3KbtOBm%2Bk%3D&reserved=0>), > but in the L1/L2 caches instead of the CUs specifically. From a cursory > check I don't see this support directly integrated into the CUs, but since > they are ClockedObject's ( > https://gem5.googlesource.com/public/gem5/+/refs/heads/develop/src/sim/clocked_object.hh#107 > <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgem5.googlesource.com%2Fpublic%2Fgem5%2F%2B%2Frefs%2Fheads%2Fdevelop%2Fsrc%2Fsim%2Fclocked_object.hh%23107&data=05%7C01%7Ckmejbaulislam%40ufl.edu%7C48e15cbe38e348f945ef08db34866a8c%7C0d4da0f84a314d76ace60a62331e1b84%7C0%7C0%7C638161524140252353%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=WTl%2BfTaLRstvaDxzlIeu28k0gTg8YpK4n860LGaMEIA%3D&reserved=0>, > > https://gem5.googlesource.com/public/gem5/+/refs/heads/develop/src/sim/ClockedObject.py#50 > <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgem5.googlesource.com%2Fpublic%2Fgem5%2F%2B%2Frefs%2Fheads%2Fdevelop%2Fsrc%2Fsim%2FClockedObject.py%2350&data=05%7C01%7Ckmejbaulislam%40ufl.edu%7C48e15cbe38e348f945ef08db34866a8c%7C0d4da0f84a314d76ace60a62331e1b84%7C0%7C0%7C638161524140252353%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=qIJHEJidxQDHK9vEow56jEpNXYgPe72g9%2FzacIJmG7o%3D&reserved=0>) > my guess is you could use the above patch as a model to add the support you > want. > > > > If you do add it, it would be great if you can add this back as a feature > for the community! > > > > Thanks, > > Matt > ------------------------------ > > *From:* Mejbaul Islam, Kazi M. via gem5-users <gem5-users@gem5.org> > *Sent:* Monday, April 3, 2023 3:49 AM > *To:* gem5-users@gem5.org <gem5-users@gem5.org> > *Cc:* Mejbaul Islam, Kazi M. <kmejbaulis...@ufl.edu> > *Subject:* [gem5-users] How to change voltage and frequency of individual > ComputeUnit for GPU? > > > > Hello, > > > > In gem5/configs/example/apu_se.py, ComputeUnit is used to build GPU. Is > there any way to change voltage and frequency of each individual > ComputeUnit? > > > > Best, > > Kazi >
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