linux-kernel - Re: [PATCH] kbuild: modinst: remove the multithread option from zstd compression

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Message-ID: <CAK7LNASB1qFv1GdxTHvLpcJu1NbWrze5VsfFRYbFMeiFv_JPhQ@mail.gmail.com>
Date: Mon, 5 Aug 2024 02:12:05 +0900
From: Masahiro Yamada <masahiroy@...nel.org>
To: sedat.dilek@...il.com
Cc: linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Nathan Chancellor <nathan@...nel.org>, Nick Terrell <terrelln@...com>, Nicolas Schier <nicolas@...sle.eu>
Subject: Re: [PATCH] kbuild: modinst: remove the multithread option from zstd compression

On Sun, Aug 4, 2024 at 3:36 PM Sedat Dilek <sedat.dilek@...il.com> wrote:
>
> On Sun, Aug 4, 2024 at 5:33 AM Masahiro Yamada <masahiroy@...nel.org> wrote:
> >
> > Parallel execution is supported by GNU Make:
> >
> >   $ make -j<N> modules_install
> >
> > It is questionable to enable multithreading within each zstd process
> > by default.
> >
> > If you still want to do it, you can use the environment variable:
> >
> >   $ ZSTD_NBTHREADS=<N> make modules_install
> >
>
> Hi Masahiro,
>
> I have some understanding problems.
>
> [ start-build.txt ]
> dileks     24225   24217  0 17:55 tty2     00:00:00 /usr/bin/perf stat
> make V=1 -k -j4 ARCH=x86_64 LLVM=1 LLVM=/opt/llvm/bin/
> PAHOLE=/opt/pahole/bin/pahole KBUILD_BUILD_HOST=iniza
> KBUILD_BUILD_USER=sedat.dilek@...il.com
> KBUILD_BUILD_TIMESTAMP=2024-08-03
> KDEB_PKGVERSION=6.10.3-1~trixie+dileks1
> LOCALVERSION=-1-amd64-clang18-kcfi olddefconfig bindeb-pkg
>
> ^^ How shall someone pass so that ... ZSTD_NBTHREADS=<N> make
> modules_install ... is used?


Option 1

$ export ZSTD_NBTHREADS=<N>
$ make V=1 -k  [snip] olddefconfig bindeb-pkg



Option 2

$ ZSTD_NBTHREADS=<N> make V=1 -k [snip] olddefconfig bindeb-pkg




>
> As far as I understood, each kernel-module file is taken - in the
> Debian build-process - sequentially file for file - ZSTD compressed
> and afterwards deleted.
> Is there a benefit when 'make -j<N>' is used?



zstd --rm -f -q foo.ko
zstd --rm -f -q bar.ko
zstd --rm -f -q baz.ko

will run in parallel with Make's -j<N> option.








-- 
Best Regards
Masahiro Yamada