Re: [U-Boot] [RFC] Allow for parallel builds and saved output

Dear Andy Fleming,

In message 1302687759-1649-1-git-send-email-afleming@freescale.com you wrote:

The MAKEALL script cleverly runs make with the appropriate options to use all of the cores on the system, but your average U-Boot build can't make much use of more than a few cores. If you happen to have a many-core server, your builds will leave most of the system idle.

...

${output_prefix}/$target. We launch up to 8 builds in parallel (with each build still being told to use n+1 cores), and wait for all 8 to finish before launching 8 more. It's not ideal, but it is faster.

How did you figure that 8 * (n+1) would be an efficient number of tasks to use? Does this not depend on a lot of factors, like number of cores, relative speed of CPUs versus I/O subsystem, etc. ?

...

+# Output +# It is now possible to save the output to a build directory. This serves +# two purposes. It allows you to keep the images for testing, and it +# allows you to launch the makes in tandem. Pass in -o <dir>, and the build +# will happen in <dir>/$target/

Hm... this conflicts with / duplicates the function of BUILD_DIR, doesn't it?

[ -d ${LOG_DIR} ] || mkdir ${LOG_DIR} || exit 1

+if [ "${output_prefix}" ] ; then

• [ -d ${output_prefix} ] || mkdir -p ${output_prefix} || exit 1
• [ -d "${output_prefix}/ERR" ] && rm -rf "${output_prefix}/ERR"
• mkdir "${output_prefix}/ERR"

+fi

Should LOG_DIR not be adjusted, too?

• [ "$output_prefix" ] && export BUILD_DIR="${output_prefix}/${target}"

Ouch. This means you are messing with user settings without warning or any indication. I don't like this.

If we have a conflict (and here we have one), there should be at least errot / warning messages.

• if [ "$output_prefix" ] ; then

• ${MAKE} clean
  

• find "${output_prefix}/$target" -type f -name '*.depend' | xargs rm
  

Why remove the .depend files and not any of the other temporary files?

• TOTAL_CNT=$((TOTAL_CNT + 1))

Um....

${CROSS_COMPILE}size ${BUILD_DIR}/u-boot \ | tee -a ${LOG_DIR}/$target.MAKELOG } @@ -650,7 +681,20 @@ build_targets() { if [ -n "${list}" ] ; then build_targets ${list} else

• 	build_target ${t}
  

• 	if [ "$output_prefix" ] ; then
  

• 		build_target ${t} &
  

• 	else
  

• 		build_target ${t}
  

• 	fi
  

• 	TOTAL_CNT=$((TOTAL_CNT + 1))
  

• 	CURRENT_COUNT=$((CURRENT_COUNT + 1))
  

• fi
  

So TOTAL_CNT and CURRENT_COUNT get only set in the "else" case?

• # Only run 8 builds concurrently
  

• if [ ${CURRENT_COUNT} -gt 8 ]; then
  

Magic number...

echo "Boards compiled: ${TOTAL_CNT}"

Is this report correct for all use cases, now?

Best regards,

Wolfgang Denk