From: Nathan Chancellor <nathan@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: x86@kernel.org, jpoimboe@redhat.com, jbaron@akamai.com,
rostedt@goodmis.org, ardb@kernel.org,
linux-kernel@vger.kernel.org, samitolvanen@google.com,
ndesaulniers@google.com, clang-built-linux@googlegroups.com
Subject: Re: [PATCH 01/13] objtool: Rewrite hashtable sizing
Date: Thu, 10 Jun 2021 11:54:50 -0700 [thread overview]
Message-ID: <7165b24e-0628-c273-f1e2-67a75358991f@kernel.org> (raw)
In-Reply-To: <YMJdYdCR0vD2t2WC@hirez.programming.kicks-ass.net>
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
next prev parent reply other threads:[~2021-06-10 18:54 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-06 19:33 [PATCH 00/13] jump_label: Yet another attempt at variable sized jump_labels Peter Zijlstra
2021-05-06 19:33 ` [PATCH 01/13] objtool: Rewrite hashtable sizing Peter Zijlstra
2021-05-12 10:41 ` Peter Zijlstra
2021-05-12 13:19 ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2021-06-10 18:14 ` [PATCH 01/13] " Nathan Chancellor
2021-06-10 18:43 ` Peter Zijlstra
2021-06-10 18:54 ` Nathan Chancellor [this message]
2021-06-10 18:50 ` Sami Tolvanen
2021-06-10 19:33 ` Peter Zijlstra
2021-06-10 19:43 ` Sami Tolvanen
2021-06-10 20:59 ` Nathan Chancellor
2021-06-14 13:19 ` [tip: objtool/core] objtool: Improve reloc hash size guestimate tip-bot2 for Peter Zijlstra
2021-05-06 19:33 ` [PATCH 02/13] x86,objtool: Dont exclude arch/x86/realmode/ Peter Zijlstra
2021-05-12 13:19 ` [tip: objtool/core] x86, objtool: " tip-bot2 for Peter Zijlstra
2021-05-06 19:33 ` [PATCH 03/13] jump_label, x86: Strip ASM jump_label support Peter Zijlstra
2021-05-12 13:19 ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2021-05-06 19:33 ` [PATCH 04/13] jump_label, x86: Factor out the __jump_table generation Peter Zijlstra
2021-05-12 13:19 ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2021-05-06 19:33 ` [PATCH 05/13] jump_label, x86: Improve error when we fail expected text Peter Zijlstra
2021-05-12 13:19 ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2021-05-06 19:33 ` [PATCH 06/13] jump_label, x86: Introduce jump_entry_size() Peter Zijlstra
2021-05-12 13:19 ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2021-05-06 19:33 ` [PATCH 07/13] jump_label, x86: Add variable length patching support Peter Zijlstra
2021-05-12 13:19 ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2021-05-13 14:16 ` [PATCH 07.5/13] jump_label,x86: Remove unused JUMP_LABEL_NOP_SIZE Peter Zijlstra
2021-05-14 7:01 ` [tip: objtool/core] jump_label/x86: " tip-bot2 for Peter Zijlstra
2021-05-06 19:34 ` [PATCH 08/13] jump_label: Free jump_entry::key bit1 for build use Peter Zijlstra
2021-05-12 13:19 ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2021-05-06 19:34 ` [PATCH 09/13] jump_label,x86: Emit short JMP Peter Zijlstra
2021-05-12 13:19 ` [tip: objtool/core] jump_label, x86: " tip-bot2 for Peter Zijlstra
2021-05-06 19:34 ` [PATCH 10/13] objtool: Decode jump_entry::key addend Peter Zijlstra
2021-05-12 13:19 ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2021-05-06 19:34 ` [PATCH 11/13] objtool: Rewrite jump_label instructions Peter Zijlstra
2021-05-12 13:19 ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2021-05-06 19:34 ` [PATCH 12/13] objtool: Provide stats for jump_labels Peter Zijlstra
2021-05-12 13:19 ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2021-05-13 14:15 ` [PATCH 12.5/13] objtool: Reflow handle_jump_alt() Peter Zijlstra
2021-05-06 19:34 ` [PATCH 13/13] jump_label,x86: Allow short NOPs Peter Zijlstra
2021-05-06 19:49 ` Peter Zijlstra
2021-05-12 13:19 ` [tip: objtool/core] jump_label, x86: " tip-bot2 for Peter Zijlstra
2021-05-18 19:50 ` Peter Zijlstra
2021-05-18 20:24 ` Peter Zijlstra
2021-05-19 0:44 ` Josh Poimboeuf
2021-05-19 6:56 ` Peter Zijlstra
2021-06-29 20:00 ` Matthew Wilcox
2021-06-29 20:35 ` Matthew Wilcox
2021-06-30 7:07 ` Peter Zijlstra
2021-06-30 7:38 ` Peter Zijlstra
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