// the testing utility
package main

import (
	"flag"
	"fmt"
	"os"
	"runtime"
)
import (
	_ "archive/tar"
	_ "archive/zip"
	_ "bufio"
	_ "bytes"
	_ "compress/bzip2"
	_ "compress/flate"
	_ "compress/gzip"
	_ "compress/lzw"
	_ "compress/zlib"
	_ "container/heap"
	_ "container/list"
	_ "container/ring"
	_ "crypto"
	_ "crypto/aes"
	_ "crypto/cipher"
	_ "crypto/des"
	_ "crypto/dsa"
	_ "crypto/ecdsa"
	_ "crypto/elliptic"
	_ "crypto/hmac"
	_ "crypto/md5"
	_ "crypto/rand"
	_ "crypto/rc4"
	_ "crypto/rsa"
	_ "crypto/sha1"
	_ "crypto/sha256"
	_ "crypto/sha512"
	_ "crypto/subtle"
	_ "crypto/tls"
	_ "crypto/x509"
	_ "crypto/x509/pkix"
	_ "database/sql"
	_ "database/sql/driver"
	_ "debug/dwarf"
	_ "debug/elf"
	_ "debug/gosym"
	_ "debug/macho"
	_ "debug/pe"
	_ "encoding/ascii85"
	_ "encoding/asn1"
	_ "encoding/base32"
	_ "encoding/base64"
	_ "encoding/binary"
	_ "encoding/csv"
	_ "encoding/gob"
	_ "encoding/hex"
	_ "encoding/json"
	_ "encoding/pem"
	_ "encoding/xml"
	_ "errors"
	_ "exp/ebnf"
	_ "exp/html"
	_ "exp/html/atom"
	_ "exp/inotify"
	_ "exp/locale/collate"
	_ "exp/locale/collate/build"
	_ "exp/norm"
	_ "exp/proxy"
	_ "exp/types"
	_ "exp/utf8string"
	_ "expvar"
	_ "flag"
	_ "fmt"
	_ "go/ast"
	_ "go/build"
	_ "go/doc"
	_ "go/parser"
	_ "go/printer"
	_ "go/scanner"
	_ "go/token"
	_ "hash"
	_ "hash/adler32"
	_ "hash/crc32"
	_ "hash/crc64"
	_ "hash/fnv"
	_ "html"
	_ "html/template"
	_ "image"
	_ "image/color"
	_ "image/draw"
	_ "image/gif"
	_ "image/jpeg"
	_ "image/png"
	_ "index/suffixarray"
	_ "io"
	_ "io/ioutil"
	_ "log"
	_ "log/syslog"
	_ "math"
	_ "math/big"
	_ "math/cmplx"
	_ "math/rand"
	_ "mime"
	_ "mime/multipart"
	_ "net"
	_ "net/http"
	_ "net/http/cgi"
	_ "net/http/fcgi"
	_ "net/http/httputil"
	_ "net/mail"
	_ "net/rpc"
	_ "net/rpc/jsonrpc"
	_ "net/smtp"
	_ "net/textproto"
	_ "net/url"
	_ "old/netchan"
	_ "os"
	_ "os/exec"
	_ "os/signal"
	_ "os/user"
	_ "path"
	_ "path/filepath"
	_ "reflect"
	_ "regexp"
	_ "regexp/syntax"
	_ "runtime"
	_ "runtime/cgo"
	_ "runtime/debug"
	_ "runtime/pprof"
	_ "sort"
	_ "strconv"
	_ "strings"
	_ "sync"
	_ "sync/atomic"
	_ "syscall"
	_ "testing/iotest"
	_ "text/scanner"
	_ "text/tabwriter"
	_ "text/template"
	_ "text/template/parse"
	_ "time"
	_ "unicode"
	_ "unicode/utf16"
	_ "unicode/utf8"
	_ "unsafe"
)

func main() {
	flagSize := flag.Int("size", 0, "alloc block size in bytes (must be a power of 2)")
	flagMem := flag.Int("mem", 0, "total mem to allocate in MB")
	flag.Parse()
	if *flagSize <= 0 || *flagSize&(*flagSize-1) != 0 || *flagMem <= 0 {
		flag.PrintDefaults()
		os.Exit(1)
	}
	sz := *flagSize
	cnt := *flagMem * (1 << 20) / sz

	var memStats runtime.MemStats

	runtime.GC()
	runtime.ReadMemStats(&memStats)
	a0 := memStats.Alloc

	for i := 0; i < cnt; i++ {
		p := make([]byte, sz)
		func(p []byte) {}(p)
	}

	runtime.GC()
	runtime.ReadMemStats(&memStats)
	a1 := memStats.Alloc

	fmt.Printf("%.2f%% pinned (%d MiB)\n", 100*float64(a1-a0)/float64(cnt)/float64(sz), a1>>20)
}