These benchmarks were written in support of Go proposal #61588, titled "proposal: runtime: software floating point for GOARM=6, 7 (not only GOARM=5)". A Change List (CL) linked in the proposal introduces new soft float options for ARM targets: GOARM=6,softfloatand GOARM=7,softfloat.
The benchmarks measure the performance of various basic operations, including arithmetic, bitwise, addition, channel-based, and atomic operations. Performance was compared between benchmarks compiled with GOARM=7,softfloat versus GOARM=5. As of now, GOARM=5 remains the only officially supported way to get soft float on ARM targets.
Benchmarks were run on a Raspberry Pi 2 with the following system details: Linux rpi2-20230613 6.1.0-11-armmp #1 SMP Debian 6.1.38-4 (2023-08-08) armv7l.
The option -test.cpu 1 was used because the intended target has a single CPU. The intended target, and inspiration for this proposal, is an armv7 device without a hardware FPU.
# GOARM=5 benchmarks
GOARCH=arm GOARM=5 GOOS=linux go test -c -o armv5.test
./armv5.test -test.bench . -test.v -test.count 6 -test.cpu 1 | tee armv5_1cpu_raw.txt
# GOARM=7,softfloat benchmarks
GOARCH=arm GOARM=7,softfloat GOOS=linux go test -c -o armv7soft.test
./armv7soft.test -test.bench . -test.v -test.count 6 -test.cpu 1 | tee armv7soft_1cpu_raw.txt
benchstat armv5_1cpu_raw.txt armv7soft_1cpu_raw.txtgoos: linux
goarch: arm
pkg: github.com/ludi317/arm-wrestle
│ armv5_1cpu_raw.txt │ armv7soft_1cpu_raw.txt │
│ sec/op │ sec/op vs base │
Float32Arithmetic 4.728µ ± 0% 4.689µ ± 0% -0.80% (p=0.002 n=6)
Int32Arithmetic 15.65n ± 0% 15.69n ± 0% +0.26% (p=0.002 n=6)
Float64Arithmetic 3.907µ ± 0% 3.877µ ± 0% -0.77% (p=0.002 n=6)
Int64Arithmetic 29.07n ± 0% 29.07n ± 0% ~ (p=0.740 n=6)
ANDconstBICconst 52.55n ± 0% 52.55n ± 0% ~ (p=0.974 n=6)
Uint64Move 22.36n ± 0% 22.36n ± 0% ~ (p=0.803 n=6)
ADD 1.049µ ± 0% 1.008µ ± 0% -3.91% (p=0.002 n=6)
ADDBICconst 20.12n ± 0% 19.01n ± 0% -5.52% (p=0.002 n=6)
ADDBICconstInt64 29.07n ± 0% 27.95n ± 0% -3.85% (p=0.002 n=6)
WithMulDAndMulF 1029.0n ± 0% 988.8n ± 0% -3.91% (p=0.002 n=6)
BitwiseInt32 8.944n ± 0% 8.945n ± 0% ~ (p=0.909 n=6)
BitwiseInt64 13.41n ± 0% 13.42n ± 0% +0.07% (p=0.013 n=6)
TrailingZeros 43.59n ± 0% 30.19n ± 0% -30.74% (p=0.002 n=6)
ProducerConsumerBufferedCh 3.875µ ± 0% 3.494µ ± 0% -9.83% (p=0.002 n=6)
ProducerConsumerBufferedChInt64 3.921µ ± 0% 3.582µ ± 0% -8.66% (p=0.002 n=6)
ProducerConsumerUnBufferedCh 5.099µ ± 0% 4.549µ ± 0% -10.80% (p=0.002 n=6)
ProducerConsumerUnBufferedChInt64 5.104µ ± 0% 4.538µ ± 0% -11.08% (p=0.002 n=6)
GetCntxct 3.884µ ± 8% 3.479µ ± 7% -10.42% (p=0.002 n=6)
CASInt32 158.9n ± 0% 161.0n ± 0% +1.32% (p=0.002 n=6)
CASInt64 502.1n ± 1% 154.4n ± 0% -69.24% (p=0.002 n=6)
CASUint64 502.1n ± 0% 152.2n ± 0% -69.68% (p=0.002 n=6)
CASUint32 158.9n ± 0% 161.0n ± 0% +1.32% (p=0.002 n=6)
CASUintptr 159.0n ± 0% 165.4n ± 0% +4.03% (p=0.002 n=6)
AtomicOperationsInt64 932.3n ± 0% 270.9n ± 0% -70.94% (p=0.002 n=6)
AtomicOperationsInt32 306.9n ± 0% 297.6n ± 0% -3.01% (p=0.002 n=6)
AtomicOperationsUint64 930.2n ± 0% 268.6n ± 0% -71.12% (p=0.002 n=6)
AtomicOperationsUint32 307.0n ± 0% 297.8n ± 0% -3.00% (p=0.002 n=6)
AtomicOperationsUintptr 308.9n ± 0% 302.2n ± 0% -2.17% (p=0.002 n=6)
AtomicOperationsBool 538.0n ± 0% 496.8n ± 0% -7.65% (p=0.002 n=6)
Mutex 44.94µ ± 0% 22.60µ ± 0% -49.70% (p=0.002 n=6)
RWMutex_Read 45.00µ ± 0% 22.65µ ± 0% -49.67% (p=0.002 n=6)
RWMutex_Write 45.22µ ± 0% 22.87µ ± 0% -49.42% (p=0.002 n=6)
WaitGroup 90.63m ± 4% 77.13m ± 4% -14.89% (p=0.002 n=6)
Channel 8.781m ± 0% 8.383m ± 0% -4.54% (p=0.002 n=6)
AtomicAdd 259.40n ± 0% 73.86n ± 0% -71.53% (p=0.002 n=6)
Once 67.11n ± 0% 64.87n ± 0% -3.33% (p=0.002 n=6)
Cond 11.126µ ± 0% 9.781µ ± 0% -12.09% (p=0.002 n=6)
Pool 774.5n ± 1% 723.2n ± 1% -6.62% (p=0.002 n=6)
MutexContended 233.4n ± 0% 233.0n ± 0% -0.19% (p=0.002 n=6)
RWMutexContendedRead 278.2n ± 0% 277.6n ± 0% -0.22% (p=0.002 n=6)
RWMutexContendedWrite 494.2n ± 0% 519.5n ± 0% +5.12% (p=0.002 n=6)
Semaphore 964.6n ± 0% 955.6n ± 0% -0.93% (p=0.002 n=6)
Mutex2 212.5n ± 0% 210.3n ± 0% -1.04% (p=0.002 n=6)
RWMutex 254.9n ± 0% 243.8n ± 0% -4.37% (p=0.002 n=6)
Channel2 964.5n ± 0% 955.6n ± 0% -0.92% (p=0.002 n=6)
MapRWMutex/Write 807.7n ± 0% 778.9n ± 0% -3.56% (p=0.002 n=6)
MapRWMutex/Read 332.0n ± 0% 331.5n ± 0% -0.15% (p=0.002 n=6)
MapMutex 501.8n ± 0% 518.8n ± 0% +3.37% (p=0.002 n=6)
geomean 757.6n 617.4n -18.50%
The same Raspberry Pi 2 also measured benchmarks on GOARM=5+keith which is GOARM=5 with Keith Randall's CL applied.
The commit prior to Keith's change was a2647f08f0c4e540540a7ae1b9ba7e668e6fed80, so the GOARM=7,softfloat patch was rebased on top of that commit too, and rerun, for parity.
System details given by uname -a: Linux raspberrypi 6.1.0-rpi4-rpi-v7 #1 SMP Raspbian 1:6.1.54-1+rpt2 (2023-10-05) armv7l GNU/Linux. Its OS has been updated since Round 1.
# GOARM=5+keith benchmarks
# build go with keith's CL applied on top of a2647f08f0c4e540540a7ae1b9ba7e668e6fed80
GOARCH=arm GOARM=5 GOOS=linux go test -c -o armv5keith.test
./armv5keith.test -test.bench . -test.v -test.count 6 -test.cpu 1 | tee armv5keith_1cpu_raw.txt
# GOARM=7,softfloat benchmarks
# build go with GOARM=7,softfloat patch applied on top of a2647f08f0c4e540540a7ae1b9ba7e668e6fed80
GOARCH=arm GOARM=7,softfloat GOOS=linux go test -c -o armv7soft.test
./armv7soft.test -test.bench . -test.v -test.count 6 -test.cpu 1 | tee armv7soft_1cpu_raw.txt
benchstat raw/round2/armv5keith_1cpu_raw.txt raw/round2/armv7soft_1cpu_raw.txtgoos: linux
goarch: arm
pkg: github.com/ludi317/arm-wrestle
cpu: ARMv7 Processor rev 5 (v7l)
│ raw/round2/armv5keith_1cpu_raw.txt │ raw/round2/armv7soft_1cpu_raw.txt │
│ sec/op │ sec/op vs base │
Float32Arithmetic 4.761µ ± 0% 4.715µ ± 0% -0.98% (p=0.002 n=6)
Int32Arithmetic 15.70n ± 0% 15.74n ± 0% +0.25% (p=0.002 n=6)
Float64Arithmetic 3.923µ ± 0% 3.898µ ± 0% -0.64% (p=0.002 n=6)
Int64Arithmetic 29.15n ± 0% 29.15n ± 0% ~ (p=0.396 n=6)
ANDconstBICconst 52.69n ± 0% 52.65n ± 0% ~ (p=0.266 n=6)
Uint64Move 22.42n ± 0% 22.42n ± 0% ~ (p=1.000 n=6)
ADD 1.060µ ± 0% 1.007µ ± 0% -5.09% (p=0.002 n=6)
ADDBICconst 20.18n ± 0% 18.95n ± 0% -6.12% (p=0.002 n=6)
ADDBICconstInt64 29.15n ± 0% 27.88n ± 0% -4.36% (p=0.002 n=6)
WithMulDAndMulF 1040.5n ± 0% 984.7n ± 0% -5.36% (p=0.002 n=6)
BitwiseInt32 8.968n ± 0% 8.919n ± 0% -0.55% (p=0.002 n=6)
BitwiseInt64 13.46n ± 0% 13.38n ± 0% -0.56% (p=0.002 n=6)
TrailingZeros 43.72n ± 0% 30.10n ± 0% -31.15% (p=0.002 n=6)
LeadingZeros 42.60n ± 0% 39.14n ± 0% -8.13% (p=0.002 n=6)
RotateLeft 114.4n ± 0% 111.0n ± 0% -2.97% (p=0.002 n=6)
OnesCount 150.2n ± 0% 144.7n ± 0% -3.73% (p=0.002 n=6)
ProducerConsumerBufferedCh 3.602µ ± 0% 3.480µ ± 0% -3.39% (p=0.002 n=6)
ProducerConsumerBufferedChInt64 3.687µ ± 0% 3.529µ ± 0% -4.29% (p=0.002 n=6)
ProducerConsumerUnBufferedCh 4.683µ ± 0% 4.492µ ± 0% -4.09% (p=0.002 n=6)
ProducerConsumerUnBufferedChInt64 4.653µ ± 0% 4.490µ ± 0% -3.50% (p=0.002 n=6)
GetCntxct 3.580µ ± 1% 3.496µ ± 1% -2.36% (p=0.002 n=6)
CASInt32 158.4n ± 0% 160.5n ± 0% +1.33% (p=0.002 n=6)
CASInt64 152.6n ± 2% 154.8n ± 0% +1.44% (p=0.015 n=6)
CASUint64 152.6n ± 1% 151.8n ± 1% ~ (p=0.117 n=6)
CASUint32 159.3n ± 0% 160.3n ± 0% +0.63% (p=0.002 n=6)
CASUintptr 159.3n ± 0% 164.8n ± 0% +3.45% (p=0.002 n=6)
AtomicOperationsInt64 269.4n ± 0% 270.0n ± 0% +0.24% (p=0.002 n=6)
AtomicOperationsInt32 307.5n ± 0% 296.8n ± 0% -3.50% (p=0.002 n=6)
AtomicOperationsUint64 269.3n ± 0% 267.7n ± 0% -0.59% (p=0.002 n=6)
AtomicOperationsUint32 307.5n ± 0% 296.9n ± 0% -3.46% (p=0.002 n=6)
AtomicOperationsUintptr 309.7n ± 0% 301.2n ± 1% -2.74% (p=0.002 n=6)
AtomicOperationsBool 539.7n ± 0% 498.2n ± 0% -7.68% (p=0.002 n=6)
Mutex 45.09µ ± 0% 22.68µ ± 0% -49.69% (p=0.002 n=6)
RWMutex_Read 45.13µ ± 0% 22.71µ ± 1% -49.69% (p=0.002 n=6)
RWMutex_Write 45.37µ ± 0% 22.90µ ± 0% -49.52% (p=0.002 n=6)
WaitGroup 77.64m ± 6% 77.01m ± 5% ~ (p=0.394 n=6)
Channel 8.816m ± 0% 8.344m ± 1% -5.35% (p=0.002 n=6)
AtomicAdd 71.80n ± 0% 73.67n ± 0% +2.61% (p=0.002 n=6)
Once 67.31n ± 0% 64.98n ± 0% -3.45% (p=0.002 n=6)
Cond 10.316µ ± 0% 9.796µ ± 0% -5.04% (p=0.002 n=6)
Pool 787.1n ± 1% 741.6n ± 2% -5.79% (p=0.002 n=6)
MutexContended 233.6n ± 1% 235.1n ± 0% +0.64% (p=0.002 n=6)
RWMutexContendedRead 276.3n ± 0% 278.6n ± 0% +0.80% (p=0.002 n=6)
RWMutexContendedWrite 499.2n ± 0% 521.5n ± 0% +4.48% (p=0.002 n=6)
Semaphore 970.6n ± 0% 967.6n ± 0% -0.30% (p=0.002 n=6)
Mutex2 213.1n ± 0% 210.9n ± 0% -1.03% (p=0.002 n=6)
RWMutex 253.5n ± 0% 242.2n ± 0% -4.46% (p=0.002 n=6)
Channel2 970.7n ± 0% 968.0n ± 0% -0.28% (p=0.002 n=6)
MapRWMutex/Write 807.4n ± 0% 790.3n ± 0% -2.12% (p=0.002 n=6)
MapRWMutex/Read 335.1n ± 0% 334.7n ± 0% -0.10% (p=0.002 n=6)
MapMutex 503.9n ± 0% 520.6n ± 0% +3.32% (p=0.002 n=6)
geomean 586.8n 550.0n -6.27%