Speed too slowly if set cpu-limit for pod in Kubernetes. Or high cpu usage with cpu-nolimit.

[penglongli]

I want to develop a file distributor based on torrent and deploy it in a Kubernetes cluster using DaemonSet. I deployed the chihaya/chihaya as the tracker.

Every node i have a torrent client:

	clientConfig := torrent.NewDefaultClientConfig()
	clientConfig.DataDir = th.op.TransferPath
	clientConfig.Seed = true
	clientConfig.ListenPort = int(th.op.TorrentPort)
	clientConfig.DefaultStorage = storage.NewFileByInfoHash(th.op.TransferPath)
	clientConfig.DisableUTP = true
	clientConfig.MaxUnverifiedBytes = 64 << 30
	clientConfig.NoDHT = false
	clientConfig.DisablePEX = false
	clientConfig.EstablishedConnsPerTorrent = 200
	clientConfig.HalfOpenConnsPerTorrent = 100
	clientConfig.TorrentPeersHighWater = 2000
	clientConfig.MaxUnverifiedBytes = 671088640

When i need distribute a file from one node, i'll generate the torrent first

pieceLength = metainfo.ChoosePieceLength(layerFileInfo.Size())
info := metainfo.Info{
	PieceLength: pieceLength,
}
if err := info.BuildFromFilePath(layerFile); err != nil {
	return nil, errors.Wrapf(err, "build torrent metainfo from file '%s' failed", layerFileInfo)
}
mi := metainfo.MetaInfo{
	InfoBytes: bencode.MustMarshal(info),
}
ih := mi.HashInfoBytes()
to, _ := th.client.AddTorrentOpt(torrent.AddTorrentOpts{
	InfoHash: ih,
	Storage: storage.NewFileOpts(storage.NewFileClientOpts{
		ClientBaseDir: layerFile,
		FilePathMaker: func(opts storage.FilePathMakerOpts) string {
			return filepath.Join(opts.File.BestPath()...)
		},
		TorrentDirMaker: nil,
		PieceCompletion: th.pc,
	}),
	ChunkSize: 128 * 1024,
})
err := to.MergeSpec(&torrent.TorrentSpec{
	InfoBytes: mi.InfoBytes,
	Trackers:  [][]string{{th.op.TorrentAnnounce}},
})

Then every torrent client(running in K8S pod) will start download this torrent. But the speed is too slowly, about 8-9MiB/s.
(The K8S pod is set cpu limit to 1c)

If i set cpu no-limit, the torrent client will use about 6c CPU, speed 60MiB/s. I don't know where the problem is.

pprof file
cpu.pb.gz