How to get function breakdown from Go profile

I've been trying to use pprof for Go on Linux, but get no function information. What am I doing wrong? Here are my build/run steps:

$ rm -f silly
$ go build -gcflags "-N -l" silly.go
$ rm -f silly.prof
$ ./silly --cpuprofile silly.prof
fib(42)=267914296
t=1.758997214s
$ go tool pprof --text silly.prof
1.75s of 1.75s total (  100%)
      flat  flat%   sum%        cum   cum%
     1.75s   100%   100%      1.75s   100%

I was expecting more detail in the output from pprof. The "t=1.75..." line indicates that the program took 1.75 sec to run, which seems ample time to collect samples at the profiler's 100 Hz sampling rate.

Here is the program:

package main

import (
    "flag"
    "fmt"
    "log"
    "os"
    "runtime/pprof"
    "time"
)

func b(n int) int {
    if n < 2 {
        return n
    } else {
        return a(n-1) + b(n-2)
    }
}

func a(n int) int {
    if n < 2 {
        return n
    } else {
        return a(n-1) + b(n-2)
    }
}

var cpuprofile = flag.String("cpuprofile", "", "write cpu profile to file")

func main() {
    flag.Parse()
    if *cpuprofile != "" {
        f, err := os.Create(*cpuprofile)
        if err != nil {
            log.Fatal(err)
        }
        pprof.StartCPUProfile(f)
        defer pprof.StopCPUProfile()
    }

    t0 := time.Now()
    fmt.Printf("fib(42)=%v\n", a(42))
    t1 := time.Now()
    fmt.Printf("t=%v\n", t1.Sub(t0))
}

I'm running on I'm on Red Hat Enterprise Linux Server release 7.0, using Go version go1.4 linux/amd64.

It turns out the mistake was omitting the binary name when invoking the pprof tool. The correct invocation is:

$ go tool pprof --text silly silly.prof
1750ms of 1750ms total (  100%)
      flat  flat%   sum%        cum   cum%
    1060ms 60.57% 60.57%     1750ms   100%  main.a
     690ms 39.43%   100%     1750ms   100%  main.b
         0     0%   100%     1750ms   100%  main.main
         0     0%   100%     1750ms   100%  runtime.goexit
         0     0%   100%     1750ms   100%  runtime.main

The line in my question omitted silly, i.e. the binary file to be profiled.

You're not going to get enough profiling samples in 1.7s. I like to profile for at least 30s, or more.

Once you have a large enough profile, try using pprof interactively (without the --text option). You'll be able to view the stats a few different ways, as well as output the various other visualization formats.

https://blog.golang.org/profiling-go-programs