diff mbox series

[RESEND,v2] Kbuild: Update config_data.gz only if KCONFIG_CONFIG materially changed

Message ID 1619197235-13860-1-git-send-email-eberman@codeaurora.org (mailing list archive)
State New
Headers show
Series [RESEND,v2] Kbuild: Update config_data.gz only if KCONFIG_CONFIG materially changed | expand

Commit Message

Elliot Berman April 23, 2021, 5 p.m. UTC
If you update the timestamp of KCONFIG_CONFIG without actually changing
anything, config_data.gz is re-generated and causes vmlinux to re-link.
When Link Time Optimization is enabled, unnecessary re-linking of
vmlinux is highly desirable since it adds several minutes to build time.

Avoid touching config_data.gz by using a script to compare the existing
config_data.gz, KCONFIG_CONFIG, or script itself to update only if any
is mismatched.  The script follows gen_kheaders.sh approach for
determing in update is needed. The script intentionally avoids
re-compressing KCONFIG_CONFIG.

The .config can be touched, for instance, by a build script which
installs the default defconfig and then applies a defconfig fragment on
top.

For a simple example on my x86 machine, I modified x86 default defconfig to set
CONFIG_IKCONFIG=y and run:
  make -j50 defconfig tiny.config vmlinux
  make -j50 defconfig tiny.config vmlinux
With this patch, vmlinux is not re-built as a result of config_data.gz
change.

Changes in v2:
 - Use md5 checksum to compare .config instead of gzip'ing again

Signed-off-by: Elliot Berman <eberman@codeaurora.org>
---
 kernel/.gitignore         |  1 +
 kernel/Makefile           |  4 +++-
 kernel/gen_config_data.sh | 31 +++++++++++++++++++++++++++++++
 3 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100755 kernel/gen_config_data.sh

Comments

Masahiro Yamada April 25, 2021, 6:50 a.m. UTC | #1
On Sat, Apr 24, 2021 at 2:02 AM Elliot Berman <eberman@codeaurora.org> wrote:


Sorry for the delay.

This patch is over-engineering.

I will apply this.
https://patchwork.kernel.org/project/linux-kbuild/patch/20210425062407.1183801-5-masahiroy@kernel.org/

The 'cmp' command is not expensive.
md5sum is unneeded.





> If you update the timestamp of KCONFIG_CONFIG without actually changing
> anything, config_data.gz is re-generated and causes vmlinux to re-link.
> When Link Time Optimization is enabled, unnecessary re-linking of
> vmlinux is highly desirable since it adds several minutes to build time.
>
> Avoid touching config_data.gz by using a script to compare the existing
> config_data.gz, KCONFIG_CONFIG, or script itself to update only if any
> is mismatched.  The script follows gen_kheaders.sh approach for
> determing in update is needed. The script intentionally avoids
> re-compressing KCONFIG_CONFIG.
>
> The .config can be touched, for instance, by a build script which
> installs the default defconfig and then applies a defconfig fragment on
> top.
>
> For a simple example on my x86 machine, I modified x86 default defconfig to set
> CONFIG_IKCONFIG=y and run:
>   make -j50 defconfig tiny.config vmlinux
>   make -j50 defconfig tiny.config vmlinux
> With this patch, vmlinux is not re-built as a result of config_data.gz
> change.
>
> Changes in v2:
>  - Use md5 checksum to compare .config instead of gzip'ing again
>
> Signed-off-by: Elliot Berman <eberman@codeaurora.org>
> ---
>  kernel/.gitignore         |  1 +
>  kernel/Makefile           |  4 +++-
>  kernel/gen_config_data.sh | 31 +++++++++++++++++++++++++++++++
>  3 files changed, 35 insertions(+), 1 deletion(-)
>  create mode 100755 kernel/gen_config_data.sh
>
> diff --git a/kernel/.gitignore b/kernel/.gitignore
> index 78701ea..a191136 100644
> --- a/kernel/.gitignore
> +++ b/kernel/.gitignore
> @@ -1,4 +1,5 @@
>  # SPDX-License-Identifier: GPL-2.0-only
> +config_data.gz.md5
>  kheaders.md5
>  timeconst.h
>  hz.bc
> diff --git a/kernel/Makefile b/kernel/Makefile
> index 320f1f3..0784bf3d 100644
> --- a/kernel/Makefile
> +++ b/kernel/Makefile
> @@ -139,8 +139,10 @@ obj-$(CONFIG_SCF_TORTURE_TEST) += scftorture.o
>  $(obj)/configs.o: $(obj)/config_data.gz
>
>  targets += config_data.gz
> +quiet_cmd_genicfg = CHK     $(obj)/config_data.gz
> +      cmd_genicfg = $(CONFIG_SHELL) $(srctree)/kernel/gen_config_data.sh $@ $<
>  $(obj)/config_data.gz: $(KCONFIG_CONFIG) FORCE
> -       $(call if_changed,gzip)
> +       $(call cmd,genicfg)
>
>  $(obj)/kheaders.o: $(obj)/kheaders_data.tar.xz
>
> diff --git a/kernel/gen_config_data.sh b/kernel/gen_config_data.sh
> new file mode 100755
> index 00000000..e9ff193
> --- /dev/null
> +++ b/kernel/gen_config_data.sh
> @@ -0,0 +1,31 @@
> +#!/bin/sh
> +# SPDX-License-Identifier: GPL-2.0
> +
> +# This script generates a compressed version of .config, if its checksum has changed
> +set -e
> +
> +this_file="$(readlink -f "$0")"
> +outfile=$1
> +infile=$2
> +
> +config_md5="$(md5sum $infile | cut -d ' ' -f1)"
> +# Any changes to this script will also cause a rebuild of config_data.
> +this_file_md5="$(md5sum $sfile | cut -d ' ' -f1)"
> +if [ -f $outfile ]; then outfile_md5="$(md5sum $outfile | cut -d ' ' -f1)"; fi
> +
> +if [ -f $outfile.md5 ] &&
> +       [ "$(head -n 1 $outfile.md5)" = "$config_md5" ] &&
> +       [ "$(head -n 2 $outfile.md5 | tail -n 1)" = "$this_file_md5" ] &&
> +       [ "$(tail -n 1 $outfile.md5)" = "$outfile_md5" ]; then
> +               exit
> +fi
> +
> +if [ "${quiet}" != "silent_" ]; then
> +       echo "  GEN     $outfile"
> +fi
> +
> +${KGZIP} -c -n -f -9 $infile > $outfile
> +
> +echo "$config_md5" > $outfile.md5
> +echo "$this_file_md5" >> $outfile.md5
> +echo "$(md5sum $outfile | cut -d ' ' -f1)" >> $outfile.md5
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>
Elliot Berman April 26, 2021, 4:16 p.m. UTC | #2
On 4/24/2021 11:50 PM, Masahiro Yamada wrote:
> On Sat, Apr 24, 2021 at 2:02 AM Elliot Berman <eberman@codeaurora.org> wrote:
> 
> 
> Sorry for the delay.

No problem!

> 
> This patch is over-engineering.

I thought so, too.

> 
> I will apply this.
> https://patchwork.kernel.org/project/linux-kbuild/patch/20210425062407.1183801-5-masahiroy@kernel.org/
> 
> The 'cmp' command is not expensive.
> md5sum is unneeded.

Thanks!

> 
>> If you update the timestamp of KCONFIG_CONFIG without actually changing
>> anything, config_data.gz is re-generated and causes vmlinux to re-link.
>> When Link Time Optimization is enabled, unnecessary re-linking of
>> vmlinux is highly desirable since it adds several minutes to build time.
>>
>> Avoid touching config_data.gz by using a script to compare the existing
>> config_data.gz, KCONFIG_CONFIG, or script itself to update only if any
>> is mismatched.  The script follows gen_kheaders.sh approach for
>> determing in update is needed. The script intentionally avoids
>> re-compressing KCONFIG_CONFIG.
>>
>> The .config can be touched, for instance, by a build script which
>> installs the default defconfig and then applies a defconfig fragment on
>> top.
>>
>> For a simple example on my x86 machine, I modified x86 default defconfig to set
>> CONFIG_IKCONFIG=y and run:
>>    make -j50 defconfig tiny.config vmlinux
>>    make -j50 defconfig tiny.config vmlinux
>> With this patch, vmlinux is not re-built as a result of config_data.gz
>> change.
>>
>> Changes in v2:
>>   - Use md5 checksum to compare .config instead of gzip'ing again
>>
>> Signed-off-by: Elliot Berman <eberman@codeaurora.org>
>> ---
>>   kernel/.gitignore         |  1 +
>>   kernel/Makefile           |  4 +++-
>>   kernel/gen_config_data.sh | 31 +++++++++++++++++++++++++++++++
>>   3 files changed, 35 insertions(+), 1 deletion(-)
>>   create mode 100755 kernel/gen_config_data.sh
>>
>> diff --git a/kernel/.gitignore b/kernel/.gitignore
>> index 78701ea..a191136 100644
>> --- a/kernel/.gitignore
>> +++ b/kernel/.gitignore
>> @@ -1,4 +1,5 @@
>>   # SPDX-License-Identifier: GPL-2.0-only
>> +config_data.gz.md5
>>   kheaders.md5
>>   timeconst.h
>>   hz.bc
>> diff --git a/kernel/Makefile b/kernel/Makefile
>> index 320f1f3..0784bf3d 100644
>> --- a/kernel/Makefile
>> +++ b/kernel/Makefile
>> @@ -139,8 +139,10 @@ obj-$(CONFIG_SCF_TORTURE_TEST) += scftorture.o
>>   $(obj)/configs.o: $(obj)/config_data.gz
>>
>>   targets += config_data.gz
>> +quiet_cmd_genicfg = CHK     $(obj)/config_data.gz
>> +      cmd_genicfg = $(CONFIG_SHELL) $(srctree)/kernel/gen_config_data.sh $@ $<
>>   $(obj)/config_data.gz: $(KCONFIG_CONFIG) FORCE
>> -       $(call if_changed,gzip)
>> +       $(call cmd,genicfg)
>>
>>   $(obj)/kheaders.o: $(obj)/kheaders_data.tar.xz
>>
>> diff --git a/kernel/gen_config_data.sh b/kernel/gen_config_data.sh
>> new file mode 100755
>> index 00000000..e9ff193
>> --- /dev/null
>> +++ b/kernel/gen_config_data.sh
>> @@ -0,0 +1,31 @@
>> +#!/bin/sh
>> +# SPDX-License-Identifier: GPL-2.0
>> +
>> +# This script generates a compressed version of .config, if its checksum has changed
>> +set -e
>> +
>> +this_file="$(readlink -f "$0")"
>> +outfile=$1
>> +infile=$2
>> +
>> +config_md5="$(md5sum $infile | cut -d ' ' -f1)"
>> +# Any changes to this script will also cause a rebuild of config_data.
>> +this_file_md5="$(md5sum $sfile | cut -d ' ' -f1)"
>> +if [ -f $outfile ]; then outfile_md5="$(md5sum $outfile | cut -d ' ' -f1)"; fi
>> +
>> +if [ -f $outfile.md5 ] &&
>> +       [ "$(head -n 1 $outfile.md5)" = "$config_md5" ] &&
>> +       [ "$(head -n 2 $outfile.md5 | tail -n 1)" = "$this_file_md5" ] &&
>> +       [ "$(tail -n 1 $outfile.md5)" = "$outfile_md5" ]; then
>> +               exit
>> +fi
>> +
>> +if [ "${quiet}" != "silent_" ]; then
>> +       echo "  GEN     $outfile"
>> +fi
>> +
>> +${KGZIP} -c -n -f -9 $infile > $outfile
>> +
>> +echo "$config_md5" > $outfile.md5
>> +echo "$this_file_md5" >> $outfile.md5
>> +echo "$(md5sum $outfile | cut -d ' ' -f1)" >> $outfile.md5
>> --
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
>> a Linux Foundation Collaborative Project
>>
> 
>
diff mbox series

Patch

diff --git a/kernel/.gitignore b/kernel/.gitignore
index 78701ea..a191136 100644
--- a/kernel/.gitignore
+++ b/kernel/.gitignore
@@ -1,4 +1,5 @@ 
 # SPDX-License-Identifier: GPL-2.0-only
+config_data.gz.md5
 kheaders.md5
 timeconst.h
 hz.bc
diff --git a/kernel/Makefile b/kernel/Makefile
index 320f1f3..0784bf3d 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -139,8 +139,10 @@  obj-$(CONFIG_SCF_TORTURE_TEST) += scftorture.o
 $(obj)/configs.o: $(obj)/config_data.gz
 
 targets += config_data.gz
+quiet_cmd_genicfg = CHK     $(obj)/config_data.gz
+      cmd_genicfg = $(CONFIG_SHELL) $(srctree)/kernel/gen_config_data.sh $@ $<
 $(obj)/config_data.gz: $(KCONFIG_CONFIG) FORCE
-	$(call if_changed,gzip)
+	$(call cmd,genicfg)
 
 $(obj)/kheaders.o: $(obj)/kheaders_data.tar.xz
 
diff --git a/kernel/gen_config_data.sh b/kernel/gen_config_data.sh
new file mode 100755
index 00000000..e9ff193
--- /dev/null
+++ b/kernel/gen_config_data.sh
@@ -0,0 +1,31 @@ 
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+# This script generates a compressed version of .config, if its checksum has changed
+set -e
+
+this_file="$(readlink -f "$0")"
+outfile=$1
+infile=$2
+
+config_md5="$(md5sum $infile | cut -d ' ' -f1)"
+# Any changes to this script will also cause a rebuild of config_data.
+this_file_md5="$(md5sum $sfile | cut -d ' ' -f1)"
+if [ -f $outfile ]; then outfile_md5="$(md5sum $outfile | cut -d ' ' -f1)"; fi
+
+if [ -f $outfile.md5 ] &&
+	[ "$(head -n 1 $outfile.md5)" = "$config_md5" ] &&
+	[ "$(head -n 2 $outfile.md5 | tail -n 1)" = "$this_file_md5" ] &&
+	[ "$(tail -n 1 $outfile.md5)" = "$outfile_md5" ]; then
+		exit
+fi
+
+if [ "${quiet}" != "silent_" ]; then
+	echo "  GEN     $outfile"
+fi
+
+${KGZIP} -c -n -f -9 $infile > $outfile
+
+echo "$config_md5" > $outfile.md5
+echo "$this_file_md5" >> $outfile.md5
+echo "$(md5sum $outfile | cut -d ' ' -f1)" >> $outfile.md5