Ludovic Courtès writes: > Christopher Baines skribis: > >> I think you're right, while I send some other changes in #68266, I think >> it's this change around make-rust-sysroot that has pretty much all the >> effects on performance. >> >> I think the tens of thousands of duplicated packages from cross-base >> that I was looking at are almost entirely coming from >> make-rust-sysroot. As Ludo mentions in [1], maybe this has something to >> do with use of cross- procedures in native-inputs, although I'm not sure >> that moving those calls out of native-inputs is a correct thing to do. >> >> I don't know what the correct approach here is, but I think something >> needs doing here to address the performance regression. > > I probably missed it in the thread: what commit caused the regression, > and how can I test any changes? I’m willing to help but I missed some > of the context. It's not a pure performance regression, more that in it's current form, rust cross derivations are very expensive to compute. It's been this way since cross-compiling was enabled in [1]. 1: https://git.savannah.gnu.org/cgit/guix.git/patch/?id=e604972d9c697302691aeb22e9c50c933a1a3c72 I've been looking at data service slowness in processing revisions over the last few weeks, and I think it's mostly down to this. Looking at the revision prior to the change [2], computing all the derivations took around 3 hours, which is ages, but still quick compared to the nearly 9 hours it took after this change [3]. 2: https://data.guix.gnu.org/revision/58bbb38c5bd2e42aab9e9408d8c9d8da3409f178 3: https://data.guix.gnu.org/revision/c9e1a72cc27925484635ae01bc4de28bf232689d Obviously having more derivations is good and that usually means more work for the data service, but in this case it seems like things can be sped up quite a bit. For testing locally, I've been computing all the derivations for i586-pc-gnu, but Efraim also posted a concise command to look at computing some cross derivations for a subset of rust packages [4]. 4: https://lists.gnu.org/archive/html/guix-devel/2024-01/msg00053.html