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Improve PackerManager benchmark

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The previous benchmark spent much of its time allocating RNGs and
generating too many random numbers. It now spends 90% of its time
hashing and half of the rest writing to files.

name             old time/op    new time/op    delta
PackerManager-8     319ms ± 1%     247ms ± 1%  -22.48%  (p=0.000 n=20+18)

name             old speed      new speed      delta
PackerManager-8   143MB/s ± 1%   213MB/s ± 1%  +48.63%  (p=0.000 n=10+18)

name             old alloc/op   new alloc/op   delta
PackerManager-8     635kB ± 0%      92kB ± 0%  -85.48%  (p=0.000 n=10+19)

name             old allocs/op  new allocs/op  delta
PackerManager-8     1.64k ± 0%     1.43k ± 0%  -12.76%  (p=0.000 n=10+20)
This commit is contained in:
greatroar 2020-03-05 20:54:52 +01:00
parent b7c3039eb2
commit b592614061
1 changed files with 37 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

51
internal/repository/packer_manager_test.go
View File

@ -5,6 +5,7 @@ import (
"io"
"math/rand"
"os"
"sync"
"testing"
"github.com/restic/restic/internal/backend/mem"
@ -25,6 +26,13 @@ func randomID(rd io.Reader) restic.ID {
const maxBlobSize = 1 << 20
func min(a, b int) int {
if a < b {
return a
}
return b
}
func saveFile(t testing.TB, be Saver, length int, f *os.File, id restic.ID) {
h := restic.Handle{Type: restic.DataFile, Name: id.String()}
t.Logf("save file %v", h)
@ -50,21 +58,17 @@ func saveFile(t testing.TB, be Saver, length int, f *os.File, id restic.ID) {
func fillPacks(t testing.TB, rnd *rand.Rand, be Saver, pm *packerManager, buf []byte) (bytes int) {
for i := 0; i < 100; i++ {
l := rnd.Intn(1 << 20)
seed := rnd.Int63()
l := rnd.Intn(maxBlobSize)
packer, err := pm.findPacker()
if err != nil {
t.Fatal(err)
}
rd := rand.New(rand.NewSource(seed))
id := randomID(rd)
id := randomID(rnd)
buf = buf[:l]
_, err = io.ReadFull(rd, buf)
if err != nil {
t.Fatal(err)
}
// Only change a few bytes so we know we're not benchmarking the RNG.
rnd.Read(buf[:min(l, 4)])
n, err := packer.Add(restic.DataBlob, id, buf)
if err != nil {
@ -109,8 +113,20 @@ func flushRemainingPacks(t testing.TB, be Saver, pm *packerManager) (bytes int)
return bytes
}
const randomSeed = 23
var (
once sync.Once
totalSize int64
)
func TestPackerManager(t *testing.T) {
rnd := rand.New(rand.NewSource(23))
bytes := testPackerManager(t)
once.Do(func() { totalSize = bytes })
}
func testPackerManager(t testing.TB) int64 {
rnd := rand.New(rand.NewSource(randomSeed))
be := mem.New()
pm := newPackerManager(be, crypto.NewRandomKey())
@ -121,23 +137,30 @@ func TestPackerManager(t *testing.T) {
bytes += flushRemainingPacks(t, be, pm)
t.Logf("saved %d bytes", bytes)
return int64(bytes)
}
func BenchmarkPackerManager(t *testing.B) {
rnd := rand.New(rand.NewSource(23))
// Run testPackerManager if it hasn't run already, to set totalSize.
once.Do(func() {
totalSize = testPackerManager(t)
})
rnd := rand.New(rand.NewSource(randomSeed))
be := &mock.Backend{
SaveFn: func(context.Context, restic.Handle, restic.RewindReader) error { return nil },
}
blobBuf := make([]byte, maxBlobSize)
t.ReportAllocs()
t.SetBytes(totalSize)
t.ResetTimer()
for i := 0; i < t.N; i++ {
bytes := 0
rnd.Seed(randomSeed)
pm := newPackerManager(be, crypto.NewRandomKey())
bytes += fillPacks(t, rnd, be, pm, blobBuf)
bytes += flushRemainingPacks(t, be, pm)
t.Logf("saved %d bytes", bytes)
fillPacks(t, rnd, be, pm, blobBuf)
flushRemainingPacks(t, be, pm)
}
}