Date:   Thu, 7 Jan 2021 13:15:16 -0800
From:   Ivan Babrou <ivan@...udflare.com>
To:     Thomas Renninger <trenn@...e.com>
Cc:     linux-pm@...r.kernel.org,
        linux-kernel <linux-kernel@...r.kernel.org>,
        kernel-team <kernel-team@...udflare.com>,
        Shuah Khan <shuah@...nel.org>
Subject: Re: [PATCH] cpupower: add Makefile dependencies for install targets

On Thu, Jan 7, 2021 at 12:59 PM Thomas Renninger <trenn@...e.com> wrote:
>
> Am Donnerstag, 7. Januar 2021, 18:42:25 CET schrieb Ivan Babrou:
> > On Thu, Jan 7, 2021 at 2:07 AM Thomas Renninger <trenn@...e.com> wrote:
> > > Am Dienstag, 5. Januar 2021, 00:57:18 CET schrieb Ivan Babrou:
> > > > This allows building cpupower in parallel rather than serially.
> > >
> > > cpupower is built serially:
> > >
> > > [ make clean ]
> > >
> > > time make
> > > real    0m3,742s
> > > user    0m3,330s
> > > sys     0m1,105s
> > >
> > > [ make clean ]
> > >
> > > time make -j10
> > > real    0m1,045s
> > > user    0m3,153s
> > > sys     0m1,037s
> > >
> > > Only advantage I see is that you can call
> > > make install-xy
> > > targets without calling the corresponding build target
> > > make xy
> > > similar to the general install target:
> > > install: all install-lib ...
> > >
> > > Not sure anyone needs this and whether all targets
> > > successfully work this way.
> > > If you'd show a useful usecase example...
> >
> > We build a bunch of kernel related tools (perf, cpupower, bpftool,
> > etc.) from our own top level Makefile, propagating parallelism
> > downwards like one should.
> I still do not understand why you do not simply build:
> Also if I call this from /tools directory I get a quick build:
> make -j20 cpupower
>
> Can you please show the make calls, ideally with a timing to better understand
> and also to reproduce the advantages this patch introduces.
> From what I can see, it only helps if one calls "sub-install" targets
> directly?

That's exactly what we do: make install directly:

/linux-5.10.5$ make -C ./tools/power/cpupower DESTDIR=/tmp/cpupower
install -j $(nproc)

make: Entering directory '/state/home/ivan/linux-5.10.5/tools/power/cpupower'
  CC       cpupower
  MSGFMT   po/de.gmo
  MSGFMT   po/fr.gmo
  MSGFMT   po/it.gmo
  MSGFMT   po/cs.gmo
/usr/bin/install -c -d /tmp/cpupower/usr/lib64
  MSGFMT   po/pt.gmo
/usr/bin/install -c -d /tmp/cpupower/usr/bin
/usr/bin/install -c -m 644 -D man/cpupower.1
/tmp/cpupower/usr/man/man1/cpupower.1
/usr/bin/install -c -d /tmp/cpupower/usr/share/locale
cp -fpR ./libcpupower.so* /tmp/cpupower/usr/lib64/
/usr/bin/install -c ./cpupower /tmp/cpupower/usr/bin
/usr/bin/install -c -m 644 -D man/cpupower-frequency-set.1
/tmp/cpupower/usr/man/man1/cpupower-frequency-set.1
make[1]: Entering directory
'/state/home/ivan/linux-5.10.5/tools/power/cpupower/bench'
for HLANG in de fr it cs pt; do \
echo '/usr/bin/install -c -m 644 -D ./po/$HLANG.gmo
/tmp/cpupower/usr/share/locale/$HLANG/LC_MESSAGES/cpupower.mo'; \
/usr/bin/install -c -m 644 -D ./po/$HLANG.gmo
/tmp/cpupower/usr/share/locale/$HLANG/LC_MESSAGES/cpupower.mo; \
done;
  CC       main.o
/usr/bin/install -c -d /tmp/cpupower/usr/share/bash-completion/completions
/usr/bin/install -c -m 644 -D ./po/$HLANG.gmo
/tmp/cpupower/usr/share/locale/$HLANG/LC_MESSAGES/cpupower.mo
  CC       parse.o
/usr/bin/install -c -m 644 -D man/cpupower-frequency-info.1
/tmp/cpupower/usr/man/man1/cpupower-frequency-info.1
  CC       system.o
/usr/bin/install: cannot stat './po/de.gmo'/usr/bin/install -c -d
/tmp/cpupower/usr/include
: No such file or directory
make[1]: Entering directory
'/state/home/ivan/linux-5.10.5/tools/power/cpupower/bench'
mkdir -p /tmp/cpupower//usr/sbin
/usr/bin/install -c -m 644 cpupower-completion.sh
'/tmp/cpupower/usr/share/bash-completion/completions/cpupower'
/usr/bin/install -c -m 644 -D ./po/$HLANG.gmo
/tmp/cpupower/usr/share/locale/$HLANG/LC_MESSAGES/cpupower.mo
  CC       benchmark.o
/usr/bin/install -c -m 644 -D man/cpupower-idle-set.1
/tmp/cpupower/usr/man/man1/cpupower-idle-set.1
/usr/bin/install: cannot stat './po/fr.gmo': No such file or directory
/usr/bin/install -c -m 644 -D ./po/$HLANG.gmo
/tmp/cpupower/usr/share/locale/$HLANG/LC_MESSAGES/cpupower.mo
mkdir -p /tmp/cpupower//usr/bin
/usr/bin/install -c -m 644 lib/cpufreq.h /tmp/cpupower/usr/include/cpufreq.h
/usr/bin/install -c -m 644 -D man/cpupower-idle-info.1
/tmp/cpupower/usr/man/man1/cpupower-idle-info.1
mkdir -p /tmp/cpupower//usr/share/doc/packages/cpupower
/usr/bin/install -c -m 644 -D ./po/$HLANG.gmo
/tmp/cpupower/usr/share/locale/$HLANG/LC_MESSAGES/cpupower.mo
/usr/bin/install -c -m 644 lib/cpuidle.h /tmp/cpupower/usr/include/cpuidle.h
mkdir -p /tmp/cpupower//etc/
/usr/bin/install -c -m 644 -D man/cpupower-set.1
/tmp/cpupower/usr/man/man1/cpupower-set.1
/usr/bin/install -c -m 644 -D ./po/$HLANG.gmo
/tmp/cpupower/usr/share/locale/$HLANG/LC_MESSAGES/cpupower.mo
install -m 755 .//cpufreq-bench /tmp/cpupower//usr/sbin/cpufreq-bench
/usr/bin/install -c -m 644 -D man/cpupower-info.1
/tmp/cpupower/usr/man/man1/cpupower-info.1
/usr/bin/install -c -m 644 -D man/cpupower-monitor.1
/tmp/cpupower/usr/man/man1/cpupower-monitor.1
install: cannot stat './/cpufreq-bench': No such file or directory
Makefile:31: recipe for target 'install' failed
make[1]: *** [install] Error 1
make[1]: Leaving directory
'/state/home/ivan/linux-5.10.5/tools/power/cpupower/bench'
Makefile:304: recipe for target 'install-bench' failed
make: *** [install-bench] Error 2
make: *** Waiting for unfinished jobs....
  CC       cpufreq-bench
make[1]: Leaving directory
'/state/home/ivan/linux-5.10.5/tools/power/cpupower/bench'
make: Leaving directory '/state/home/ivan/linux-5.10.5/tools/power/cpupower'

It works with -j 1. My patch makes it work with arbitrary parallelism,
same as any other tool we build internally (perf, bpftool, turbostat,
etc.).

> And I still do not understand why things should be more parallel now.
>
> > Without this patch we have to remove parallelism for cpupower,
> Why?
>
> > which doesn't seem like a very clean thing
> > to do, especially if you consider that it's 3x faster with parallelism
> > enabled in wall clock terms.
> Sure, you want to build in parallel. I still do not understand how this
> patch helps in this regard.
>
> BTW, I recently had a bunch of userspace tools Makefile patches.
> I'd like to add you to CC for a review if they are not submitted already.

Don't know how useful I can be, but feel free to.

>     Thomas
>
>

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