From: Yonghong Song <yhs@fb.com>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
<dwarves@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Bill Wendling <morbo@google.com>, <bpf@vger.kernel.org>,
<kernel-team@fb.com>
Subject: Re: [PATCH dwarves v3 0/3] permit merging all dwarf cu's for clang lto built binary
Date: Wed, 31 Mar 2021 08:08:36 -0700 [thread overview]
Message-ID: <0bca2e79-ed26-f483-88e3-f3225504a6e4@fb.com> (raw)
In-Reply-To: <YGR/Cc3/39V0kRuj@kernel.org>
On 3/31/21 6:54 AM, Arnaldo Carvalho de Melo wrote:
> Em Tue, Mar 30, 2021 at 08:20:20PM -0700, Yonghong Song escreveu:
>> On 3/30/21 11:24 AM, Arnaldo Carvalho de Melo wrote:
>>> Em Tue, Mar 30, 2021 at 03:08:06PM -0300, Arnaldo Carvalho de Melo escreveu:
>>>> [acme@five pahole]$ fullcircle tcp_bbr.o
>>>> [acme@five pahole]$
>
>>>> This one is dealt with, doing some more tests and looking at that
>>>> array[] versus array[0].
>
>>> I've pushed what I have to the main repos at kernel.org and github,
>>> please check, I'll continue from there.
>
>> Looks good. Thanks!
>
>> I will try to experiment with an alternative way ([1]) to check whether
>> cross-cu reference happens or not. But at least checking flags
>> approach can be adapted to gcc (if we want after comparing the alternative)
>> since gcc always has flags in dwarf.
>
>> [1] https://lore.kernel.org/bpf/d34a3d62-bae8-3a30-26b6-4e5e8efcd0af@fb.com/T/#m1b0b1206091c19a90b15d054aa26239101289f84
>
> I thought about some other method, like adding a ELF note to vmlinux
> stating that this was built with LTO, that would be the fastest way, I
Adding to the ELF .notes is a great idea. Let me explore it. Thanks!
> think. If that note wasn't there, then we would fallback to looking at
> inter CU references, that way we would have the best of both worlds and
> wouldn't incur in per-CU DW_AT_producer overheads with the flags for
> each object file.
Totally agree.
>
> - Arnaldo
>
next prev parent reply other threads:[~2021-03-31 15:09 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-28 20:14 [PATCH dwarves v3 0/3] permit merging all dwarf cu's for clang lto built binary Yonghong Song
2021-03-28 20:14 ` [PATCH dwarves v3 1/3] dwarf_loader: permits flexible HASHTAGS__BITS Yonghong Song
2021-03-28 20:14 ` [PATCH dwarves v3 2/3] dwarf_loader: factor out common code to initialize a cu Yonghong Song
2021-03-28 20:14 ` [PATCH dwarves v3 3/3] dwarf_loader: permit merging all dwarf cu's for clang lto built binary Yonghong Song
2021-03-30 20:08 ` Bill Wendling
2021-03-30 20:15 ` Yonghong Song
2021-03-30 21:44 ` Bill Wendling
2021-03-30 22:28 ` Yonghong Song
2021-03-30 23:25 ` Bill Wendling
2021-03-29 17:40 ` [PATCH dwarves v3 0/3] " Arnaldo Carvalho de Melo
2021-03-30 15:10 ` Arnaldo Carvalho de Melo
2021-03-30 18:08 ` Arnaldo Carvalho de Melo
2021-03-30 18:24 ` Arnaldo Carvalho de Melo
2021-03-31 3:20 ` Yonghong Song
2021-03-31 13:54 ` Arnaldo Carvalho de Melo
2021-03-31 15:08 ` Yonghong Song [this message]
2021-03-31 0:29 ` Yonghong Song
2021-03-29 23:14 ` Nick Desaulniers
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