Messages in this thread | | | Subject | Re: [PATCH 01/13] objtool: Rewrite hashtable sizing | From | Nathan Chancellor <> | Date | Thu, 10 Jun 2021 11:54:50 -0700 |
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On 6/10/2021 11:43 AM, Peter Zijlstra wrote: > On Thu, Jun 10, 2021 at 11:14:51AM -0700, Nathan Chancellor wrote: > >> This patch as commit 25cf0d8aa2a3 ("objtool: Rewrite hashtable sizing") >> in -tip causes a massive compile time regression with allmodconfig + >> ThinLTO. > > Moo... the allyesconfig builds I used it on were much faster, but that > was on regular GCC vmlinux.o after linking. > >> Adding Sami because I am not sure why this patch would have much of an impact >> in relation to LTO. https://git.kernel.org/tip/25cf0d8aa2a3 is the patch in >> question. >> >> If I can provide any further information or help debug, please let me know. >> >> If you are interested in reproducing this locally, you will need a >> fairly recent LLVM stack (I used the stable release/12.x branch) and to >> cherry-pick commit 976aac5f8829 ("kcsan: Fix debugfs initcall return >> type") to fix an unrelated build failure. My script [2] can build a >> self-contained toolchain fairly quickly if you cannot get one from your >> package manager. A command like below will speed up the build a bit: > > Would something like llvm-13 from Debian be good enough? > > $ clang-13 --version > Debian clang version 13.0.0-++20210418105309+a0898f0cecc7-1~exp1 > Target: x86_64-pc-linux-gnu > Thread model: posix > InstalledDir: /usr/bin >
Yes, that would work. That is what we use in our CI.
Looks like Sami gave a reply that explains it.
Cheers, Nathan
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