RFC: ksize.sh - kernel component size build summary report generator

From: Darren Hart
Date: Thu Sep 22 2011 - 03:19:23 EST

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Build gurus and bit-misers,

As part of an effort to generate minimal configs as well as find areas that may
benefit from a size audit, I've written the following script to try and identify
how much each top level area contributes to the final vmlinux image. The goal is
different from the bloat-o-meter script in that I am not so much interested in
the delta between two kernels, but rather on the size of the individual
components of a single kernel.

It currently relies on the built-in.o hierarchy. This approach has some
(now-)obvious flaws in that it doesn't deal well with the couple *.a files, or
the .o files omitted from the arch/x86/built-in.o which are instead linked
directly into the vmlinux image during the final link step (presumably due to
some ordering requirement?).

There are also some discrepancies I'd like to understand and hopefully account
for better. For example, the sum of arch/x86/*/built-in.o is larger than
arch/x86/built-in.o. I believe this is due mostly to things like
arch/x86/(lib|pci|power)/built-in.o not being linked into
arch/x86/built-in.o, but rather linked directly into vmlinux.

In other areas, a lot of the size comes from the *.o files at the same level as
the built-in.o. Summing these up can result in a much larger sum than the size
of the built-in.o. I have included the *.o size and count as an aid to
understanding the numbers, but it is lacking.

I strip vmlinux and 'find . -name "*.o"' before running the script.

It is still written in shell, but any additional complexity will likely cause
me to rewrite it in python.

I have included an example report from a fairly minimal atom .config after the
script.

Questions:
o Are there better ways to determine how much size each component contributes to
vmlinux?
o Does anyone else find this useful?
o Does the format make sense?
o Would any additional data be useful to others?
o Would converting this into a make target make sense? We might be able to make
use of make's knowledge of what gets linked where to improve how we group
components.

#!/bin/sh
#
# Copyright (c) 2011, Intel Corporation.
# All rights reserved.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
#
#
# Display details of the kernel build size, broken up by built-in.o. Sort
# the objects by size, omitting anything under 1k by default. Run from the
# top level kernel build directory.
#
# Author: Darren Hart <dvhart@xxxxxxxxxxxxxxx>
#

clean_up() {
rm -f $TLDFILE
rm -f $DFILE
exit
}

# Uncomment or set in env to print objects under 1K in size
# VERBOSE=1
if [ -n "$VERBOSE" ]; then
VERBOSE_LIMIT=0
else
VERBOSE_LIMIT=1024
fi

if [ -z "$ARCH" ]; then
ARCH="x86"
fi

# Check that we are in a Linux build directory
if [ ! -f vmlinux ]; then
echo "ERROR: vmlinux not found"
exit 1
fi

trap clean_up SIGHUP SIGINT SIGTERM

# format_stat() - Format the output of stat
# Print the size of the file in bytes, its name, an optional comment
# and a warning if the object has not been stripped.
# $1 file
# $2 comment
format_stat() {
if [ ! -f $1 ]; then return; fi

STRIP=""
if [ "$(file $1 | grep -c 'not stripped')" != "0" ]; then
STRIP="(not stripped)"
fi
SIZE="$(stat --printf='%s' $1)"
if [ "$SIZE" -ge "$VERBOSE_LIMIT" ]; then
stat --printf="%10s\t%n $2 $STRIP\n" $1
fi
}

TLDFILE=$(mktemp ksize.tmp.XXXXXXXXXX)
DFILE=$(mktemp ksize.tmp.XXXXXXXXXX)

echo "Linux Kernel Images"
echo "======================================================================"
# FIXME: adapt for other architectures and image types
format_stat arch/$ARCH/boot/bzImage "(compressed)"
format_stat vmlinux "(uncompressed)"
echo ""

echo "Top Level Summary"
echo "======================================================================"
format_stat vmlinux "(uncompressed)"
echo "----------------------------------------------------------------------"
for O in arch/$ARCH/built-in.o */built-in.o .tmp_kallsyms2.o; do
if [ -f "$O" ]; then
format_stat $O
fi
done | sort -gr | tee $TLDFILE
echo "----------------------------------------------------------------------"
BI_SUM=$(awk '{S += $1} END {print S}' $TLDFILE)
VM_SIZE=$(stat --printf="%s" vmlinux)
printf "%10d\tTotal from listed objects\n" $BI_SUM
printf "%10d\tTotal from unlisted object files\n" $(($VM_SIZE - $BI_SUM))
echo ""

echo "Detailed Breakdown"
echo "======================================================================"
for TB in $(cat $TLDFILE | awk '{print $2;}'); do
# Skip files other than built-in.o (such as .tmp_kallsyms2.o)
if [ ! $(basename "$TB") = "built-in.o" ]; then continue; fi

format_stat $TB
BUILTINS=$(find $(dirname $TB) -maxdepth 2 -name built-in.o)

# Print a heading line if we will be printing any lower level built-ins
PRINT_TOTALS=false
for B in $BUILTINS; do
SIZE="$(stat --printf='%s' $B)"
if [ "$B" != "$TB" -a "$SIZE" -ge "$VERBOSE_LIMIT" ]; then
echo "----------------------------------------------------------------------"
PRINT_TOTALS=true
break
fi
done

# Print details of each built-in.o one level down
for B in $BUILTINS; do
if [ "$B" != "$TB" ]; then
format_stat $B
fi
done | sort -gr | tee $DFILE

if [ $PRINT_TOTALS = true ]; then
echo " --------------------------------------------------------------------"
BI_SUM=$(awk '{S += $1} END {print S}' $DFILE)
TL_SIZE=$(stat --printf="%s" $TB)
O_SUM=$(stat --printf="%s %n\n" $(dirname $TB)/*.o | grep -v built-in.o | awk '{S += $1} END {print S}')
O_CNT=$(ls $(dirname $TB)/*.o | grep -v built-in.o | wc -l)
printf "%10d\tTotal from listed objects\n" $BI_SUM
printf "%10d\tTotal from unlisted object files\n" $(($TL_SIZE - $BI_SUM))
printf "%10d\tSum of $O_CNT top-level object files\n" $O_SUM
fi
echo ""
done

clean_up

Linux Kernel Images
======================================================================
1052768 arch/x86/boot/bzImage (compressed)
2030932 vmlinux (uncompressed)

Top Level Summary
======================================================================
2030932 vmlinux (uncompressed)
----------------------------------------------------------------------
699652 drivers/built-in.o
357208 fs/built-in.o
258588 arch/x86/built-in.o
254256 kernel/built-in.o
164068 mm/built-in.o
144084 .tmp_kallsyms2.o
44100 block/built-in.o
29048 lib/built-in.o
14188 init/built-in.o
3644 security/built-in.o
----------------------------------------------------------------------
1968836 Total from listed objects
62096 Total from unlisted object files

Detailed Breakdown
======================================================================
699652 drivers/built-in.o
----------------------------------------------------------------------
233928 drivers/acpi/built-in.o
142644 drivers/tty/built-in.o
66372 drivers/pci/built-in.o
56048 drivers/mmc/built-in.o
45768 drivers/base/built-in.o
35880 drivers/input/built-in.o
26728 drivers/pnp/built-in.o
9408 drivers/char/built-in.o
8660 drivers/video/built-in.o
7188 drivers/thermal/built-in.o
6984 drivers/cpufreq/built-in.o
6892 drivers/cpuidle/built-in.o
6464 drivers/gpu/built-in.o
5440 drivers/firmware/built-in.o
4832 drivers/idle/built-in.o
4452 drivers/usb/built-in.o
4284 drivers/power/built-in.o
4172 drivers/spi/built-in.o
3048 drivers/clocksource/built-in.o
--------------------------------------------------------------------
679192 Total from listed objects
20460 Total from unlisted object files
0 Sum of 0 top-level object files

357208 fs/built-in.o
----------------------------------------------------------------------
78112 fs/ext3/built-in.o
44976 fs/proc/built-in.o
24000 fs/jbd/built-in.o
15108 fs/sysfs/built-in.o
9360 fs/partitions/built-in.o
3988 fs/nls/built-in.o
2872 fs/ramfs/built-in.o
2844 fs/devpts/built-in.o
--------------------------------------------------------------------
181260 Total from listed objects
175948 Total from unlisted object files
215600 Sum of 48 top-level object files

258588 arch/x86/built-in.o
----------------------------------------------------------------------
217484 arch/x86/kernel/built-in.o
42112 arch/x86/pci/built-in.o
31352 arch/x86/mm/built-in.o
6372 arch/x86/platform/built-in.o
5796 arch/x86/vdso/built-in.o
1648 arch/x86/power/built-in.o
--------------------------------------------------------------------
304764 Total from listed objects
-46176 Total from unlisted object files
0 Sum of 0 top-level object files

254256 kernel/built-in.o
----------------------------------------------------------------------
31828 kernel/events/built-in.o
28372 kernel/time/built-in.o
15368 kernel/irq/built-in.o
4164 kernel/power/built-in.o
--------------------------------------------------------------------
79732 Total from listed objects
174524 Total from unlisted object files
217400 Sum of 56 top-level object files

164068 mm/built-in.o

44100 block/built-in.o

29048 lib/built-in.o

14188 init/built-in.o

3644 security/built-in.o

--
Darren Hart
Intel Open Source Technology Center
Yocto Project - Linux Kernel
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Next message: Sakkinen, Jarkko: "Re: [PATCH] Smack: Use secureexec with SMACK64EXEC"
Previous message: Lily Jing: "I can supply you fabric you are looking for"
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