f82cc0ee80
It is possible to use QEMU and kvm to measure the time taken by U-Boot to hand off to Linux. Add a script to support this and print the resulting time. This requires a fair bit of setup; see the script for details. Signed-off-by: Simon Glass <sjg@chromium.org>
94 lines
2.5 KiB
Bash
Executable File
94 lines
2.5 KiB
Bash
Executable File
#!/bin/bash
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# SPDX-License-Identifier: GPL-2.0-or-later
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# .. code-block:: bash
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# qemu-boot-timer.sh
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#
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# Runs qboot (or builds and starts U-Boot) and measures how long it takes to
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# start Linux. Must be run in the U-Boot source directory.
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#
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# See:
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# https://stefano-garzarella.github.io/posts/2019-08-24-qemu-linux-boot-time/
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# https://github.com/stefano-garzarella/qemu-boot-time.git
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#
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# You will need to first install tracing tools, e.g.:
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#
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# sudo apt install linux-tools-common linux-tools-generic linux-tools-`uname -r`
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#
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# and also change files and directories below
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#
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# Example usage to test qboot:
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# $ ./contrib/qemu-boot-timer.sh
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# qemu-system-x86_64: terminating on signal 15 from pid 3548708 (bash)
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# 1) pid 3548829
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# qemu_init_end: 48.352996
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# fw_start: 48.480586 (+0.12759)
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# linux_start_boot: 66.16271 (+17.682124)
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# Exit point 0: 66.37544 (+0.21273)
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#
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# That shows a time of 17.7 milliseconds for qboot itself
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# Enable this to boot qboot instead of U-Boot
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#QBOOT=-QB
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# Linux version to boot (read from /boot)
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version=6.8.0-60-generic
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# UUID of root disk within your disk image, which must be called root.img
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uuid=bcfdda4a-8249-4f40-9f0f-7c1a76b6cbe8
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# Set up directories to use
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DIR=/scratch/sglass/qemu-boot-time/
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PERF_DATA=perf.data
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export PERF_EXEC_PATH=/scratch/sglass/linux/tools/perf
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# No settings below here:
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# Turn on tracing in Linux
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sudo bash <<EOF
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echo 1 > /sys/kernel/debug/tracing/events/kvm/enable
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echo -1 > /proc/sys/kernel/perf_event_paranoid
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mount -o remount,mode=755 /sys/kernel/debug
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mount -o remount,mode=755 /sys/kernel/debug/tracing
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EOF
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# Start recording
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sleep 1
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cd $DIR
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sudo perf record -a -e kvm:kvm_entry -e kvm:kvm_pio -e sched:sched_process_exec \
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-o $PERF_DATA 2> /tmp/trace.log &
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PERF_PID=$!
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# Run QEWU with qboot or U-Boot (builds U-Boot automatically)
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sleep 1
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cd ~/u
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./scripts/build-qemu -a x86 ${QBOOT} -rs -v -K /boot/vmlinuz-${version} \
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-k -d root.img -I /boot/initrd.img-${version} -C -U ${uuid} -s \
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2>&1 >/tmp/qemu.log &
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while [[ -z "$QEMU_PID" ]]; do
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QEMU_PID=$(pgrep qemu-system-x86)
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done
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# Wait for it to boot
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sleep 5
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# Kill QEMU and the perf process
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kill $QEMU_PID
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sleep 1
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kill $PERF_PID
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wait $PERF_PID
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# Adjust permissions on perf data
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cd $DIR
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sudo chmod a+r $PERF_DATA
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# Generate the Python script to permit access to the trace
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perf script -g python 2>/dev/null
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# Run our script which looks for timing points and prints the results
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perf script -s ~/perf-script.py -s ${DIR}/perf-script/qemu-perf-script.py \
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-i $PERF_DATA
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