Logo Questions Linux Laravel Mysql Ubuntu Git Menu
HTML CSS JAVASCRIPT SQL PYTHON PHP BOOTSTRAP JAVA JQUERY R React Kotlin
 

Measure FLOPS in Go

Tags:

benchmarking

go

I would like to write a go program to benchmark my CPU and figure out my laptop's GFLOPS.

func benchmarkFlopTime(){
    num_operations := int(100000000)
    var timeArray[] time.Duration;

    var result float64
    for i:=0; i < num_operations; i++ {
        t1 := time.Now()
        result = 1.0 + 312.232
        elapsed := time.Since(t1)
        timeArray = append(timeArray, elapsed)
        result += 1.0
    }

    fmt.Println("Result (ns):", float64(sumTimeArray(timeArray))/float64(time.Duration(num_operations)))
}

Ouput1: Result (ns): 9.99604753ns

Interpretation:

This code gives me around 0.1 GFLOPS ((1sec/10ns)/10^-9). I know my CPU can do something like 8 Operations Per Cycle and I only do one, so I can have a factor 8, let's assume I've 1GFLOPS

Problems:

  • Although, the theoretical number of GFLOPS for my laptop with a 2.5GHZ i7, 8 cores, should be: 8*2.5*8 = 160GFLOPS. I'm far below this result.

I precise that I don't activate the optimisation when I compile go install -gcflags '-N -l' github.com/golang/cpu-benchmark.

Can we explain this value, far below the theoretical value? Is Go ok to measure that?

like image 999
nlassaux Avatar asked Feb 02 '16 19:02

nlassaux

1 Answers

Here's a (simplistic) Go benchmark which times a loop and twenty floating point operations.

package main

import (
    "fmt"
    "math"
    "runtime"
    "testing"
    "time"
)

var (
    f  float64
    e  float64 = math.E
    pi float64 = math.Pi
)

const nFlop = 20 // benchmarkFloatOps

func benchmarkFloatOps(n int) {
    for i := 0; i < n; i++ {
        f = pi + e
        f = pi - e
        f = pi * e
        f = pi / e
        f = pi + e
        f = pi - e
        f = pi * e
        f = pi / e
        f = pi + e
        f = pi - e
        f = pi * e
        f = pi / e
        f = pi + e
        f = pi - e
        f = pi * e
        f = pi / e
        f = pi + e
        f = pi - e
        f = pi * e
        f = pi / e
    }
}

func BenchmarkFloatOps(b *testing.B) {
    benchmarkFloatOps(b.N)
}

func Results(t time.Duration, n int, nFlop int) {
    fmt.Println(
        t, nFlop*n, "ops",
        float64(t)/float64(time.Duration((nFlop*n))), "ns/op",
    )
}

func main() {
    runtime.GOMAXPROCS(1)

    // testing benchmark
    br := testing.Benchmark(BenchmarkFloatOps)
    Results(br.T, br.N, nFlop)

    // manual benchmark
    n := br.N
    start := time.Now()
    benchmarkFloatOps(n)
    end := time.Now()
    elapsed := end.Sub(start)
    Results(elapsed, n, nFlop)
}

Output: Intel i7-6700 CPU 3.40GHz:

1.296967371s 4000000000 ops 0.32424184275 ns/op
1.299078813s 4000000000 ops 0.32476970325 ns/op

Go pseudocode for benchmarkFloatOps:

$ go tool compile -S flops.go

"".benchmarkFloatOps t=1 size=592 value=0 args=0x8 locals=0x0
    0x0000 00000 (flops.go:19)  TEXT    "".benchmarkFloatOps(SB), $0-8
    0x0000 00000 (flops.go:19)  NOP
    0x0000 00000 (flops.go:19)  NOP
    0x0000 00000 (flops.go:19)  MOVQ    "".n+8(FP), CX
    0x0005 00005 (flops.go:19)  FUNCDATA    $0, gclocals·5184031d3a32a42d85027f073f873668(SB)
    0x0005 00005 (flops.go:19)  FUNCDATA    $1, gclocals·33cdeccccebe80329f1fdbee7f5874cb(SB)
    0x0005 00005 (flops.go:20)  MOVQ    $0, AX
    0x0007 00007 (flops.go:20)  CMPQ    AX, CX
    0x000a 00010 (flops.go:20)  JGE $0, 588
    0x0010 00016 (flops.go:21)  MOVSD   "".pi(SB), X0
    0x0018 00024 (flops.go:21)  MOVSD   "".e(SB), X1
    0x0020 00032 (flops.go:21)  ADDSD   X1, X0
    0x0024 00036 (flops.go:21)  MOVSD   X0, "".f(SB)
    0x002c 00044 (flops.go:22)  MOVSD   "".pi(SB), X0
    0x0034 00052 (flops.go:22)  MOVSD   "".e(SB), X1
    0x003c 00060 (flops.go:22)  SUBSD   X1, X0
    0x0040 00064 (flops.go:22)  MOVSD   X0, "".f(SB)
    0x0048 00072 (flops.go:23)  MOVSD   "".pi(SB), X0
    0x0050 00080 (flops.go:23)  MOVSD   "".e(SB), X1
    0x0058 00088 (flops.go:23)  MULSD   X1, X0
    0x005c 00092 (flops.go:23)  MOVSD   X0, "".f(SB)
    0x0064 00100 (flops.go:24)  MOVSD   "".pi(SB), X0
    0x006c 00108 (flops.go:24)  MOVSD   "".e(SB), X1
    0x0074 00116 (flops.go:24)  DIVSD   X1, X0
    0x0078 00120 (flops.go:24)  MOVSD   X0, "".f(SB)
    0x0080 00128 (flops.go:25)  MOVSD   "".pi(SB), X0
    0x0088 00136 (flops.go:25)  MOVSD   "".e(SB), X1
    0x0090 00144 (flops.go:25)  ADDSD   X1, X0
    0x0094 00148 (flops.go:25)  MOVSD   X0, "".f(SB)
    0x009c 00156 (flops.go:26)  MOVSD   "".pi(SB), X0
    0x00a4 00164 (flops.go:26)  MOVSD   "".e(SB), X1
    0x00ac 00172 (flops.go:26)  SUBSD   X1, X0
    0x00b0 00176 (flops.go:26)  MOVSD   X0, "".f(SB)
    0x00b8 00184 (flops.go:27)  MOVSD   "".pi(SB), X0
    0x00c0 00192 (flops.go:27)  MOVSD   "".e(SB), X1
    0x00c8 00200 (flops.go:27)  MULSD   X1, X0
    0x00cc 00204 (flops.go:27)  MOVSD   X0, "".f(SB)
    0x00d4 00212 (flops.go:28)  MOVSD   "".pi(SB), X0
    0x00dc 00220 (flops.go:28)  MOVSD   "".e(SB), X1
    0x00e4 00228 (flops.go:28)  DIVSD   X1, X0
    0x00e8 00232 (flops.go:28)  MOVSD   X0, "".f(SB)
    0x00f0 00240 (flops.go:29)  MOVSD   "".pi(SB), X0
    0x00f8 00248 (flops.go:29)  MOVSD   "".e(SB), X1
    0x0100 00256 (flops.go:29)  ADDSD   X1, X0
    0x0104 00260 (flops.go:29)  MOVSD   X0, "".f(SB)
    0x010c 00268 (flops.go:30)  MOVSD   "".pi(SB), X0
    0x0114 00276 (flops.go:30)  MOVSD   "".e(SB), X1
    0x011c 00284 (flops.go:30)  SUBSD   X1, X0
    0x0120 00288 (flops.go:30)  MOVSD   X0, "".f(SB)
    0x0128 00296 (flops.go:31)  MOVSD   "".pi(SB), X0
    0x0130 00304 (flops.go:31)  MOVSD   "".e(SB), X1
    0x0138 00312 (flops.go:31)  MULSD   X1, X0
    0x013c 00316 (flops.go:31)  MOVSD   X0, "".f(SB)
    0x0144 00324 (flops.go:32)  MOVSD   "".pi(SB), X0
    0x014c 00332 (flops.go:32)  MOVSD   "".e(SB), X1
    0x0154 00340 (flops.go:32)  DIVSD   X1, X0
    0x0158 00344 (flops.go:32)  MOVSD   X0, "".f(SB)
    0x0160 00352 (flops.go:33)  MOVSD   "".pi(SB), X0
    0x0168 00360 (flops.go:33)  MOVSD   "".e(SB), X1
    0x0170 00368 (flops.go:33)  ADDSD   X1, X0
    0x0174 00372 (flops.go:33)  MOVSD   X0, "".f(SB)
    0x017c 00380 (flops.go:34)  MOVSD   "".pi(SB), X0
    0x0184 00388 (flops.go:34)  MOVSD   "".e(SB), X1
    0x018c 00396 (flops.go:34)  SUBSD   X1, X0
    0x0190 00400 (flops.go:34)  MOVSD   X0, "".f(SB)
    0x0198 00408 (flops.go:35)  MOVSD   "".pi(SB), X0
    0x01a0 00416 (flops.go:35)  MOVSD   "".e(SB), X1
    0x01a8 00424 (flops.go:35)  MULSD   X1, X0
    0x01ac 00428 (flops.go:35)  MOVSD   X0, "".f(SB)
    0x01b4 00436 (flops.go:36)  MOVSD   "".pi(SB), X0
    0x01bc 00444 (flops.go:36)  MOVSD   "".e(SB), X1
    0x01c4 00452 (flops.go:36)  DIVSD   X1, X0
    0x01c8 00456 (flops.go:36)  MOVSD   X0, "".f(SB)
    0x01d0 00464 (flops.go:37)  MOVSD   "".pi(SB), X0
    0x01d8 00472 (flops.go:37)  MOVSD   "".e(SB), X1
    0x01e0 00480 (flops.go:37)  ADDSD   X1, X0
    0x01e4 00484 (flops.go:37)  MOVSD   X0, "".f(SB)
    0x01ec 00492 (flops.go:38)  MOVSD   "".pi(SB), X0
    0x01f4 00500 (flops.go:38)  MOVSD   "".e(SB), X1
    0x01fc 00508 (flops.go:38)  SUBSD   X1, X0
    0x0200 00512 (flops.go:38)  MOVSD   X0, "".f(SB)
    0x0208 00520 (flops.go:39)  MOVSD   "".pi(SB), X0
    0x0210 00528 (flops.go:39)  MOVSD   "".e(SB), X1
    0x0218 00536 (flops.go:39)  MULSD   X1, X0
    0x021c 00540 (flops.go:39)  MOVSD   X0, "".f(SB)
    0x0224 00548 (flops.go:40)  MOVSD   "".pi(SB), X0
    0x022c 00556 (flops.go:40)  MOVSD   "".e(SB), X1
    0x0234 00564 (flops.go:40)  DIVSD   X1, X0
    0x0238 00568 (flops.go:40)  MOVSD   X0, "".f(SB)
    0x0240 00576 (flops.go:20)  INCQ    AX
    0x0243 00579 (flops.go:20)  NOP
    0x0243 00579 (flops.go:20)  CMPQ    AX, CX
    0x0246 00582 (flops.go:20)  JLT $0, 16
    0x024c 00588 (flops.go:42)  RET

Go object code for benchmarkFloatOps:

$ go build flops.go && go tool objdump -s benchmarkFloatOps ./flops

TEXT main.benchmarkFloatOps(SB) /home/peter/Dropbox/gopath/src/so/benchmark/flops.go
    flops.go:19 0x401000    488b4c2408      MOVQ 0x8(SP), CX
    flops.go:20 0x401005    31c0            XORL AX, AX
    flops.go:20 0x401007    4839c8          CMPQ CX, AX
    flops.go:20 0x40100a    0f8d3c020000        JGE 0x40124c
    flops.go:21 0x401010    f20f1005e8801b00    REPNE MOVSD_XMM 0x1b80e8(IP), X0
    flops.go:21 0x401018    f20f100dd8801b00    REPNE MOVSD_XMM 0x1b80d8(IP), X1
    flops.go:21 0x401020    f20f58c1        REPNE ADDSD X1, X0
    flops.go:21 0x401024    f20f110544451e00    REPNE MOVSD_XMM X0, 0x1e4544(IP)
    flops.go:22 0x40102c    f20f1005cc801b00    REPNE MOVSD_XMM 0x1b80cc(IP), X0
    flops.go:22 0x401034    f20f100dbc801b00    REPNE MOVSD_XMM 0x1b80bc(IP), X1
    flops.go:22 0x40103c    f20f5cc1        REPNE SUBSD X1, X0
    flops.go:22 0x401040    f20f110528451e00    REPNE MOVSD_XMM X0, 0x1e4528(IP)
    flops.go:23 0x401048    f20f1005b0801b00    REPNE MOVSD_XMM 0x1b80b0(IP), X0
    flops.go:23 0x401050    f20f100da0801b00    REPNE MOVSD_XMM 0x1b80a0(IP), X1
    flops.go:23 0x401058    f20f59c1        REPNE MULSD X1, X0
    flops.go:23 0x40105c    f20f11050c451e00    REPNE MOVSD_XMM X0, 0x1e450c(IP)
    flops.go:24 0x401064    f20f100594801b00    REPNE MOVSD_XMM 0x1b8094(IP), X0
    flops.go:24 0x40106c    f20f100d84801b00    REPNE MOVSD_XMM 0x1b8084(IP), X1
    flops.go:24 0x401074    f20f5ec1        REPNE DIVSD X1, X0
    flops.go:24 0x401078    f20f1105f0441e00    REPNE MOVSD_XMM X0, 0x1e44f0(IP)
    flops.go:25 0x401080    f20f100578801b00    REPNE MOVSD_XMM 0x1b8078(IP), X0
    flops.go:25 0x401088    f20f100d68801b00    REPNE MOVSD_XMM 0x1b8068(IP), X1
    flops.go:25 0x401090    f20f58c1        REPNE ADDSD X1, X0
    flops.go:25 0x401094    f20f1105d4441e00    REPNE MOVSD_XMM X0, 0x1e44d4(IP)
    flops.go:26 0x40109c    f20f10055c801b00    REPNE MOVSD_XMM 0x1b805c(IP), X0
    flops.go:26 0x4010a4    f20f100d4c801b00    REPNE MOVSD_XMM 0x1b804c(IP), X1
    flops.go:26 0x4010ac    f20f5cc1        REPNE SUBSD X1, X0
    flops.go:26 0x4010b0    f20f1105b8441e00    REPNE MOVSD_XMM X0, 0x1e44b8(IP)
    flops.go:27 0x4010b8    f20f100540801b00    REPNE MOVSD_XMM 0x1b8040(IP), X0
    flops.go:27 0x4010c0    f20f100d30801b00    REPNE MOVSD_XMM 0x1b8030(IP), X1
    flops.go:27 0x4010c8    f20f59c1        REPNE MULSD X1, X0
    flops.go:27 0x4010cc    f20f11059c441e00    REPNE MOVSD_XMM X0, 0x1e449c(IP)
    flops.go:28 0x4010d4    f20f100524801b00    REPNE MOVSD_XMM 0x1b8024(IP), X0
    flops.go:28 0x4010dc    f20f100d14801b00    REPNE MOVSD_XMM 0x1b8014(IP), X1
    flops.go:28 0x4010e4    f20f5ec1        REPNE DIVSD X1, X0
    flops.go:28 0x4010e8    f20f110580441e00    REPNE MOVSD_XMM X0, 0x1e4480(IP)
    flops.go:29 0x4010f0    f20f100508801b00    REPNE MOVSD_XMM 0x1b8008(IP), X0
    flops.go:29 0x4010f8    f20f100df87f1b00    REPNE MOVSD_XMM 0x1b7ff8(IP), X1
    flops.go:29 0x401100    f20f58c1        REPNE ADDSD X1, X0
    flops.go:29 0x401104    f20f110564441e00    REPNE MOVSD_XMM X0, 0x1e4464(IP)
    flops.go:30 0x40110c    f20f1005ec7f1b00    REPNE MOVSD_XMM 0x1b7fec(IP), X0
    flops.go:30 0x401114    f20f100ddc7f1b00    REPNE MOVSD_XMM 0x1b7fdc(IP), X1
    flops.go:30 0x40111c    f20f5cc1        REPNE SUBSD X1, X0
    flops.go:30 0x401120    f20f110548441e00    REPNE MOVSD_XMM X0, 0x1e4448(IP)
    flops.go:31 0x401128    f20f1005d07f1b00    REPNE MOVSD_XMM 0x1b7fd0(IP), X0
    flops.go:31 0x401130    f20f100dc07f1b00    REPNE MOVSD_XMM 0x1b7fc0(IP), X1
    flops.go:31 0x401138    f20f59c1        REPNE MULSD X1, X0
    flops.go:31 0x40113c    f20f11052c441e00    REPNE MOVSD_XMM X0, 0x1e442c(IP)
    flops.go:32 0x401144    f20f1005b47f1b00    REPNE MOVSD_XMM 0x1b7fb4(IP), X0
    flops.go:32 0x40114c    f20f100da47f1b00    REPNE MOVSD_XMM 0x1b7fa4(IP), X1
    flops.go:32 0x401154    f20f5ec1        REPNE DIVSD X1, X0
    flops.go:32 0x401158    f20f110510441e00    REPNE MOVSD_XMM X0, 0x1e4410(IP)
    flops.go:33 0x401160    f20f1005987f1b00    REPNE MOVSD_XMM 0x1b7f98(IP), X0
    flops.go:33 0x401168    f20f100d887f1b00    REPNE MOVSD_XMM 0x1b7f88(IP), X1
    flops.go:33 0x401170    f20f58c1        REPNE ADDSD X1, X0
    flops.go:33 0x401174    f20f1105f4431e00    REPNE MOVSD_XMM X0, 0x1e43f4(IP)
    flops.go:34 0x40117c    f20f10057c7f1b00    REPNE MOVSD_XMM 0x1b7f7c(IP), X0
    flops.go:34 0x401184    f20f100d6c7f1b00    REPNE MOVSD_XMM 0x1b7f6c(IP), X1
    flops.go:34 0x40118c    f20f5cc1        REPNE SUBSD X1, X0
    flops.go:34 0x401190    f20f1105d8431e00    REPNE MOVSD_XMM X0, 0x1e43d8(IP)
    flops.go:35 0x401198    f20f1005607f1b00    REPNE MOVSD_XMM 0x1b7f60(IP), X0
    flops.go:35 0x4011a0    f20f100d507f1b00    REPNE MOVSD_XMM 0x1b7f50(IP), X1
    flops.go:35 0x4011a8    f20f59c1        REPNE MULSD X1, X0
    flops.go:35 0x4011ac    f20f1105bc431e00    REPNE MOVSD_XMM X0, 0x1e43bc(IP)
    flops.go:36 0x4011b4    f20f1005447f1b00    REPNE MOVSD_XMM 0x1b7f44(IP), X0
    flops.go:36 0x4011bc    f20f100d347f1b00    REPNE MOVSD_XMM 0x1b7f34(IP), X1
    flops.go:36 0x4011c4    f20f5ec1        REPNE DIVSD X1, X0
    flops.go:36 0x4011c8    f20f1105a0431e00    REPNE MOVSD_XMM X0, 0x1e43a0(IP)
    flops.go:37 0x4011d0    f20f1005287f1b00    REPNE MOVSD_XMM 0x1b7f28(IP), X0
    flops.go:37 0x4011d8    f20f100d187f1b00    REPNE MOVSD_XMM 0x1b7f18(IP), X1
    flops.go:37 0x4011e0    f20f58c1        REPNE ADDSD X1, X0
    flops.go:37 0x4011e4    f20f110584431e00    REPNE MOVSD_XMM X0, 0x1e4384(IP)
    flops.go:38 0x4011ec    f20f10050c7f1b00    REPNE MOVSD_XMM 0x1b7f0c(IP), X0
    flops.go:38 0x4011f4    f20f100dfc7e1b00    REPNE MOVSD_XMM 0x1b7efc(IP), X1
    flops.go:38 0x4011fc    f20f5cc1        REPNE SUBSD X1, X0
    flops.go:38 0x401200    f20f110568431e00    REPNE MOVSD_XMM X0, 0x1e4368(IP)
    flops.go:39 0x401208    f20f1005f07e1b00    REPNE MOVSD_XMM 0x1b7ef0(IP), X0
    flops.go:39 0x401210    f20f100de07e1b00    REPNE MOVSD_XMM 0x1b7ee0(IP), X1
    flops.go:39 0x401218    f20f59c1        REPNE MULSD X1, X0
    flops.go:39 0x40121c    f20f11054c431e00    REPNE MOVSD_XMM X0, 0x1e434c(IP)
    flops.go:40 0x401224    f20f1005d47e1b00    REPNE MOVSD_XMM 0x1b7ed4(IP), X0
    flops.go:40 0x40122c    f20f100dc47e1b00    REPNE MOVSD_XMM 0x1b7ec4(IP), X1
    flops.go:40 0x401234    f20f5ec1        REPNE DIVSD X1, X0
    flops.go:40 0x401238    f20f110530431e00    REPNE MOVSD_XMM X0, 0x1e4330(IP)
    flops.go:20 0x401240    48ffc0          INCQ AX
    flops.go:20 0x401243    4839c8          CMPQ CX, AX
    flops.go:20 0x401246    0f8cc4fdffff        JL 0x401010
    flops.go:42 0x40124c    c3          RET
like image 82
peterSO Avatar answered Oct 22 '22 13:10

peterSO
Sign in to Comment

Related questions

Doing a "IN Array" query on google app engine datastore with golang
read from secondary with mgo.Monotonic
Handling multiple errors
Difference between for loop construct vs range keyword in go
how to config golang plugins in pycharm?
go: cannot find GOROOT directory: c:\go
Golang variable inside json field tag
Simplifying repetitive error handling with julienschmidt httprouter
How to represent PostgreSQL interval in Go
Go Scheduler who fills the local runqueue of P?
How can I initialize a nested map inside a struct in Go?
Reverse SSH with golang
Do Clearing slices in golang guarantees garbage collection?
Need help getting past 'reflect: NumField of non-struct type'
Cross-compilation of cgo (for darwin) fails
How can I get time.Time in Golang protobuf v3 struct?
Go "this"-keyword
How to create a daemon process in Golang? [duplicate]
How do I return from func main in Go?
Go Get Not Downloading to SRC Folder

Donate For Us

If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!