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We weren't using cs_base in the hash calculations before. Since the
arm front end moved a chunk of flags in a378206a20 (target/arm: Move
mode specific TB flags to tb->cs_base) they comprise of an important
part of the execution state.
Widen the tb_hash_func to include cs_base and expand to qemu_xxhash8()
to accommodate it.
My initial benchmark shows very little difference in the
runtime.
Before:
armhf
➜ hyperfine -w 2 -m 20 "./arm-softmmu/qemu-system-arm -cpu cortex-a15 -machine type=virt,highmem=off -display none -m 2048 -serial mon:stdio -netdev user,id=unet,hostfwd=tcp::2222-:22 -device virtio-net-pci,netdev=unet -device virtio-scsi-pci -blockdev driver=raw,node-name=hd,discard=unmap,file.driver=host_device,file.filename=/dev/zen-disk/debian-bullseye-armhf -device scsi-hd,drive=hd -smp 4 -kernel /home/alex/lsrc/linux.git/builds/arm/arch/arm/boot/zImage -append 'console=ttyAMA0 root=/dev/sda2 systemd.unit=benchmark.service' -snapshot"
Benchmark 1: ./arm-softmmu/qemu-system-arm -cpu cortex-a15 -machine type=virt,highmem=off -display none -m 2048 -serial mon:stdio -netdev user,id=unet,hostfwd=tcp::2222-:22 -device virtio-net-pci,netdev=unet -device virtio-scsi-pci -blockdev driver=raw,node-name=hd,discard=unmap,file.driver=host_device,file.filename=/dev/zen-disk/debian-bullseye-armhf -device scsi-hd,drive=hd -smp 4 -kernel /home/alex/lsrc/linux.git/builds/arm/arch/arm/boot/zImage -append 'console=ttyAMA0 root=/dev/sda2 systemd.unit=benchmark.service' -snapshot
Time (mean ± σ): 24.627 s ± 2.708 s [User: 34.309 s, System: 1.797 s]
Range (min … max): 22.345 s … 29.864 s 20 runs
arm64
➜ hyperfine -w 2 -n 20 "./qemu-system-aarch64 -cpu max,pauth-impdef=on -machine type=virt,virtualization=on,gic-version=3 -display none -serial mon:stdio -netdev user,id=unet,hostfwd=tcp::2222-:22,hostfwd=tcp::1234-:1234 -device virtio-net-pci,netdev=unet -device virtio-scsi-pci -blockdev driver=raw,node-name=hd,discard=unmap,file.driver=host_device,file.filename=/dev/zen-disk/debian-bullseye-arm64 -device scsi-hd,drive=hd -smp 4 -kernel ~/lsrc/linux.git/builds/arm64/arch/arm64/boot/Image.gz -append 'console=ttyAMA0 root=/dev/sda2 systemd.unit=benchmark-pigz.service' -snapshot"
Benchmark 1: 20
Time (mean ± σ): 62.559 s ± 2.917 s [User: 189.115 s, System: 4.089 s]
Range (min … max): 59.997 s … 70.153 s 10 runs
After:
armhf
Benchmark 1: ./arm-softmmu/qemu-system-arm -cpu cortex-a15 -machine type=virt,highmem=off -display none -m 2048 -serial mon:stdio -netdev user,id=unet,hostfwd=tcp::2222-:22 -device virtio-net-pci,netdev=unet -device virtio-scsi-pci -blockdev driver=raw,node-name=hd,discard=unmap,file.driver=host_device,file.filename=/dev/zen-disk/debian-bullseye-armhf -device scsi-hd,drive=hd -smp 4 -kernel /home/alex/lsrc/linux.git/builds/arm/arch/arm/boot/zImage -append 'console=ttyAMA0 root=/dev/sda2 systemd.unit=benchmark.service' -snapshot
Time (mean ± σ): 24.223 s ± 2.151 s [User: 34.284 s, System: 1.906 s]
Range (min … max): 22.000 s … 28.476 s 20 runs
arm64
hyperfine -w 2 -n 20 "./qemu-system-aarch64 -cpu max,pauth-impdef=on -machine type=virt,virtualization=on,gic-version=3 -display none -serial mon:stdio -netdev user,id=unet,hostfwd=tcp::2222-:22,hostfwd=tcp::1234-:1234 -device virtio-net-pci,netdev=unet -device virtio-scsi-pci -blockdev driver=raw,node-name=hd,discard=unmap,file.driver=host_device,file.filename=/dev/zen-disk/debian-bullseye-arm64 -device scsi-hd,drive=hd -smp 4 -kernel ~/lsrc/linux.git/builds/arm64/arch/arm64/boot/Image.gz -append 'console=ttyAMA0 root=/dev/sda2 systemd.unit=benchmark-pigz.service' -snapshot"
Benchmark 1: 20
Time (mean ± σ): 62.769 s ± 1.978 s [User: 188.431 s, System: 5.269 s]
Range (min … max): 60.285 s … 66.868 s 10 runs
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230526165401.574474-12-alex.bennee@linaro.org
Message-Id: <20230524133952.3971948-11-alex.bennee@linaro.org>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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Now we no longer have dynamic state affecting things we can remove the
additional fields in cpu.h and simplify the TB hash calculation.
For the benchmark:
hyperfine -w 2 -m 20 \
"./arm-softmmu/qemu-system-arm -cpu cortex-a15 \
-machine type=virt,highmem=off \
-display none -m 2048 \
-serial mon:stdio \
-netdev user,id=unet,hostfwd=tcp::2222-:22 \
-device virtio-net-pci,netdev=unet \
-device virtio-scsi-pci \
-blockdev driver=raw,node-name=hd,discard=unmap,file.driver=host_device,file.filename=/dev/zen-disk/debian-bullseye-armhf \
-device scsi-hd,drive=hd -smp 4 \
-kernel /home/alex/lsrc/linux.git/builds/arm/arch/arm/boot/zImage \
-append 'console=ttyAMA0 root=/dev/sda2 systemd.unit=benchmark.service' \
-snapshot"
It has a marginal effect on runtime, before:
Time (mean ± σ): 26.279 s ± 2.438 s [User: 41.113 s, System: 1.843 s]
Range (min … max): 24.420 s … 32.565 s 20 runs
after:
Time (mean ± σ): 24.440 s ± 2.885 s [User: 34.474 s, System: 2.028 s]
Range (min … max): 21.663 s … 29.937 s 20 runs
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1358
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 20230526165401.574474-10-alex.bennee@linaro.org
Message-Id: <20230524133952.3971948-9-alex.bennee@linaro.org>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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