linux-kernel - Re: [PATCH] kbuild: Remove debug info from kallsyms linking

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Date:   Mon, 2 Mar 2020 22:10:42 -0800
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     Masahiro Yamada <masahiroy@...nel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Alexei Starovoitov <ast@...nel.org>, bpf <bpf@...r.kernel.org>
Subject: Re: [PATCH] kbuild: Remove debug info from kallsyms linking

On Mon, Mar 2, 2020 at 8:48 PM Kees Cook <keescook@...omium.org> wrote:
>
> On Mon, Feb 24, 2020 at 09:16:17PM -0800, Kees Cook wrote:
> > When CONFIG_DEBUG_INFO is enabled, the two kallsyms linking steps spend
> > time collecting and writing the dwarf sections to the temporary output
> > files. kallsyms does not need this information, and leaving it off
> > halves their linking time. This is especially noticeable without
> > CONFIG_DEBUG_INFO_REDUCED. The BTF linking stage, however, does still
> > need those details.
> >
> > Refactor the BTF and kallsyms generation stages slightly for more
> > regularized temporary names. Skip debug during kallsyms links.
> >
> > For a full debug info build with BTF, my link time goes from 1m06s to
> > 0m54s, saving about 12 seconds, or 18%.
> >
> > Signed-off-by: Kees Cook <keescook@...omium.org>
>
> Ping. Masahiro what do you think of this? It saves me a fair bit of time
> on the link stage... I bet the BPF folks would be interested too. :)

The build time improvement sound great.
Could you please resubmit for bpf-next tree?
So we can test and apply properly?
Thanks!