From: Kees Cook <keescook@chromium.org>
To: Sami Tolvanen <samitolvanen@google.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>,
Michal Marek <michal.lkml@markovi.net>,
linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kbuild: reuse vmlinux.o in vmlinux_link
Date: Thu, 21 May 2020 15:08:53 -0700 [thread overview]
Message-ID: <202005211506.2700F86@keescook> (raw)
In-Reply-To: <20200521202716.193316-1-samitolvanen@google.com>
On Thu, May 21, 2020 at 01:27:16PM -0700, Sami Tolvanen wrote:
> Instead of linking all compilation units again each time vmlinux_link is
> called, reuse vmlinux.o from modpost_link.
>
> With x86_64 allyesconfig, vmlinux_link is called three times and reusing
> vmlinux.o reduces the build time ~38 seconds on my system (59% reduction
> in the time spent in vmlinux_link).
Nice! Any time savings at final link is a big cumulative win.
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> ---
> scripts/link-vmlinux.sh | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> index d09ab4afbda4..c6cc4305950c 100755
> --- a/scripts/link-vmlinux.sh
> +++ b/scripts/link-vmlinux.sh
> @@ -77,11 +77,8 @@ vmlinux_link()
>
> if [ "${SRCARCH}" != "um" ]; then
> objects="--whole-archive \
> - ${KBUILD_VMLINUX_OBJS} \
> + vmlinux.o \
> --no-whole-archive \
> - --start-group \
> - ${KBUILD_VMLINUX_LIBS} \
> - --end-group \
> ${@}"
>
> ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \
I think the "um" case can be updated as well too, yes?
Also, I think the comment above modpost_link() needs to be updated now
to reflect the nature of how vmlinux.o gets used after this patch.
--
Kees Cook
next prev parent reply other threads:[~2020-05-21 22:08 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-21 20:27 [PATCH] kbuild: reuse vmlinux.o in vmlinux_link Sami Tolvanen
2020-05-21 22:08 ` Kees Cook [this message]
2020-05-22 18:16 ` Masahiro Yamada
2020-05-21 22:18 ` Kees Cook
2020-05-22 17:41 ` Masahiro Yamada
2020-05-22 17:44 ` Masahiro Yamada
2020-05-23 10:06 ` Nicholas Piggin
2020-05-23 15:12 ` Masahiro Yamada
2020-05-23 16:53 ` Sam Ravnborg
2020-05-25 6:13 ` Masahiro Yamada
2020-06-15 21:47 ` Sami Tolvanen
2020-06-16 3:22 ` Masahiro Yamada
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