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From:   Thorsten Leemhuis <linux@leemhuis.info>
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To:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Cc:     lwn@lwn.net
Subject: kcbench, the Linux kernel compile benchmark, version 0.9.0 is out
Message-ID: <5b2e2f50-a222-81e9-4383-c503d9a8fbe4@leemhuis.info>
Date:   Tue, 23 Jun 2020 11:54:37 +0200
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Sender: linux-kernel-owner@vger.kernel.org
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TWIMC: I released version 0.9.0 of kcbench, a simple Linux kernel
compile benchmark. It basically downloads a Linux version (which one
depends on the compiler used), extracts it, creates a configuration
('defconfig' by default), before it compiles a kernel ('vmlinux') in a
temporary directory ('O=/tmp/foo/') while measuring the time it takes to
build. It compiles a few kernels that way using different number of jobs
(make -j #). After each run kcbench prints the time it took and how many
kernels the machine can build per hour at this rate.

This is how it looks:


> [cttest@localhost ~]$ kcbench

> Processor:           Intel(R) Core(TM) i5-3350P CPU @ 3.10GHz [4 CPUs]

> Cpufreq; Memory:     powersave [intel_pstate]; 7895 MiB

> Linux running:       5.6.2-125.vanilla.knurd.1.fc31.x86_64 [x86_64]

> Compiler:            gcc (GCC) 9.3.1 20200317 (Red Hat 9.3.1-1)

> Linux compiled:      4.19.0 [/home/thl/.cache/kcbench/linux-4.19/]

> Config; Environment: defconfig; CCACHE_DISABLE="1"

> Build command:       make vmlinux

> Filling caches:      This might take a while... Done

> Run 1 (-j 4):        288.16 seconds / 12.49 kernels/hour [P:384%]

> Run 2 (-j 4):        288.19 seconds / 12.49 kernels/hour [P:384%]

> Run 3 (-j 6):        291.01 seconds / 12.37 kernels/hour [P:384%]

> Run 4 (-j 6):        291.28 seconds / 12.36 kernels/hour [P:385%]


You can use the benchmark to compare different machines, just make sure
they use a similar compiler. Kcbench can be useful for stress tests,
too. It's also a good tool to find the optimal number of jobs for
compiling source code, as 'just use all cores' sometimes is not the
fastest setting, as a quick test on an AMD Ryzen Threadripper 3990X (64
cores/128 threads) recently showed:


> [cttest@localhost ~]$ kcbench -s 5.3 -n 1 -m

> Processor:            AMD Ryzen Threadripper 3990X 64-Core Processor [128 CPUs]

> Cpufreq; Memory:      Unknown; 63736 MByte RAM

> Linux running:        5.6.0-0.rc2.git0.1.vanilla.knurd.2.fc31.x86_64

> Compiler used:        gcc (GCC) 9.2.1 20190827 (Red Hat 9.2.1-1)

> Linux compiled:       5.3.0 [/home/cttest/.cache/kcbench/linux-5.3/]

> Config; Environment:  defconfig; CCACHE_DISABLE="1"

> Build command:        make vmlinux

> Run 1 (-j 128):       260.43 seconds / 13.82 kernels/hour

> Run 2 (-j 136):       262.67 seconds / 13.71 kernels/hour

> Run 3 (-j 64):        215.54 seconds / 16.70 kernels/hour

> Run 4 (-j 72):        215.97 seconds / 16.67 kernels/hour

(this is a quote from the man-page, which has a few more results)

For more general information about kcbench see:

 * its project page:
https://gitlab.com/knurd42/kcbench/

 * its README:
https://gitlab.com/knurd42/kcbench/-/blob/master/README.md

 * the man-page for kcbench, which tries to compile one Linux kernel
really fast by using many jobs:
https://gitlab.com/knurd42/kcbench/-/raw/master/kcbench.man1.md

 * the man-page for kcbenchrate (which is new with 0.9.0 [thx arnd for
the suggestion]), which by default compiles one kernel on each CPU using
one job to measure the rate and keep the all cores busy all the time:
https://gitlab.com/knurd42/kcbench/-/raw/master/kcbenchrate.man1.md

 * the release page for kcbench 0.9.0, which list all its major
improvements:
https://gitlab.com/knurd42/kcbench/-/releases/v0.9.0


To quickly outline the potential briefly, here is what a
'kcbench --help' will show:

> Usage: kcbench [options]

> 

> Compile a Linux kernel and measure the time it takes.

> 

> Available options:

>  -b, --bypass                 -- bypass cache fill run and measure immediately

>  -d, --detailedresults        -- print more detailed results

>  -i, --iterations <int>       -- number or iterations per job

>  -j, --jobs <int> (*)         -- number of jobs to use ('make -j #')

>  -m, --modconfig              -- build using 'allmodconfig vmlinux modules'

>  -o, --outputdir <dir>        -- compile in <dir>/kcbench/ ('make O=#')

>  -q, --quiet                  -- quiet

>  -s, --src (<dir>|<version>)  -- take Linux sources from <dir>; if not found

>                                  try ~/.cache/kcbench/linux-<version>/ and

>                                  /usr/share/kcdata/linux-<version>/; if still

>                                  not found download <version> automatically.

>  -v, --verbose (*)            -- increase verboselevel

> 

>      --add-make-args <str>    -- pass <str> to make call ('make <str> vmlinux')

>      --cc <exec>              -- use specified target compiler ('CC=#')

>      --cross-compile <arch>   -- cross compile for <arch>

>      --crosscomp-scheme <str> -- naming scheme for cross compiler

>      --hostcc <exec>          -- use specified host compiler ('HOSTCC=#')

>      --infinite               -- run endlessly

>      --llvm                   -- sets 'LLVM=1' to use clang and LLVM tools

>      --no-download            -- never download anything automatically

>      --savefailedlogs <dir>   -- save log from failed compilations in <dir>

> 

>  -h, --help                   -- show this text

>  -V, --version                -- output program version

> 

> (*) -- option can be passed multiple times


Ciao, Thorsten

P.S.: kcbench is written in Bash, as it started quite small and grew a
lot over time. Maybe at this point bash might not be the best choice,
but OTOH it's something that runs nearly everywhere; it also understood
by a lot of people, which makes it easy to adjust to specific needs.