Perhaps I am confused as well. I would have to investigate to see what the precise situation was.
On Thu, Jan 23, 2025 at 12:40 PM ÉRDI Gergő <ge...@erdi.hu> wrote: > I'll get back to you with details as I can. > > But one thing I noticed is that contrary to my expectations, when > replacing the ModDetails with fresh ones, the real cost comes not from the > fact that we have to re-evaluate the various parts of the ModDetails, but > rather the call to `fillModDetails` itself! > > In other words, I can replicate most of the slowdown by calling > `fillModDetails` on the interfaces in the HPT but throwing its result away > and keeping the HPT as is. This sounds like bad news to me. > > Your remark that there are HomeModInfos referenced outside the HPT > confuses me. I thought the whole reason this could work, and the whole > reason I can see memory usage improvement, is because the HomeModInfos are > not stored outside the HPT? If they are, home come my replacing them in > the HPT with fresh ModDetails helps with memory usage instead of making it > worse? > > On Thu, 23 Jan 2025, Matthew Pickering wrote: > > > That's good news. > > > > I don't think the first idea will do very much as there are other > references to the > > final "HomeModInfo" not stored in the HPT. > > > > Have you constructed a time profile to determine why the runtime is > higher? With the > > second approach you are certainly trading space usage for repeating work. > > > > If you actually do have a forest, then ideally you would replace the > ModDetails after > > it will never be used again. > > > > You are likely also missing other patches important for memory usage. > > > > * https://gitlab.haskell.org/ghc/ghc/-/merge_requests/12582 > > * https://gitlab.haskell.org/ghc/ghc/-/merge_requests/12347 > > > > I can't comment about the 17 HPT, what do the retainer stacks look like > in ghc-debug? > > > > PS. Please use eventlog2html so the profiles are readable! You can use > it on .hp > > profiles. > > > > Cheers, > > > > Matt
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