forks/go-ethereum
1
0
Fork 1
mirror of https://github.com/ethereum/go-ethereum.git synced 2026-07-25 14:16:44 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 1

eth/downloader: adaptive quality of service tuning

Browse source
This commit is contained in:
Péter Szilágyi 2016-06-01 18:07:25 +03:00
parent 828e1e35fd
commit c02170de4e
3 changed files with 159 additions and 41 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

133
eth/downloader/downloader.go
View file

@ -54,14 +54,14 @@ var (
blockTargetRTT = 3 * time.Second / 2 // [eth/61] Target time for completing a block retrieval request
blockTTL = 3 * blockTargetRTT // [eth/61] Maximum time allowance before a block request is considered expired
headerTargetRTT = time.Second // [eth/62] Target time for completing a header retrieval request (only for measurements for now)
headerTTL = 3 * time.Second // [eth/62] Time it takes for a header request to time out
bodyTargetRTT = 3 * time.Second / 2 // [eth/62] Target time for completing a block body retrieval request
bodyTTL = 3 * bodyTargetRTT // [eth/62] Maximum time allowance before a block body request is considered expired
receiptTargetRTT = 3 * time.Second / 2 // [eth/63] Target time for completing a receipt retrieval request
receiptTTL = 3 * receiptTargetRTT // [eth/63] Maximum time allowance before a receipt request is considered expired
stateTargetRTT = 2 * time.Second / 2 // [eth/63] Target time for completing a state trie retrieval request
stateTTL = 3 * stateTargetRTT // [eth/63] Maximum time allowance before a node data request is considered expired
rttMinEstimate = 2 * time.Second // Minimum round-trip time to target for download requests
rttMaxEstimate = 20 * time.Second // Maximum rount-trip time to target for download requests
rttMinConfidence = 0.1 // Worse confidence factor in our estimated RTT value
rttTTLScaling = 3 // Constant scaling factor for RTT -> TTL conversion
qosTuningPeers = 5 // Number of peers to tune based on (best peers)
qosConfidenceCap = 10 // Number of peers above which not to modify RTT confidence
qosTuningImpact = 0.25 // Impact that a new tuning target has on the previous value
maxQueuedHashes = 32 * 1024 // [eth/61] Maximum number of hashes to queue for import (DOS protection)
maxQueuedHeaders = 32 * 1024 // [eth/62] Maximum number of headers to queue for import (DOS protection)
@ -110,7 +110,9 @@ type Downloader struct {
queue *queue // Scheduler for selecting the hashes to download
peers *peerSet // Set of active peers from which download can proceed
interrupt int32 // Atomic boolean to signal termination
rttEstimate uint64 // Round trip time to target for download requests
rttConfidence uint64 // Confidence in the estimated RTT (unit: millionths to allow atomic ops)
interrupt int32 // Atomic boolean to signal termination
// Statistics
syncStatsChainOrigin uint64 // Origin block number where syncing started at
@ -169,11 +171,13 @@ func New(stateDb ethdb.Database, mux *event.TypeMux, hasHeader headerCheckFn, ha
headFastBlock headFastBlockRetrievalFn, commitHeadBlock headBlockCommitterFn, getTd tdRetrievalFn, insertHeaders headerChainInsertFn,
insertBlocks blockChainInsertFn, insertReceipts receiptChainInsertFn, rollback chainRollbackFn, dropPeer peerDropFn) *Downloader {
return &Downloader{
dl := &Downloader{
mode: FullSync,
mux: mux,
queue: newQueue(stateDb),
peers: newPeerSet(),
rttEstimate: uint64(rttMaxEstimate),
rttConfidence: uint64(1000000),
hasHeader: hasHeader,
hasBlockAndState: hasBlockAndState,
getHeader: getHeader,
@ -201,6 +205,8 @@ func New(stateDb ethdb.Database, mux *event.TypeMux, hasHeader headerCheckFn, ha
stateWakeCh: make(chan bool, 1),
headerProcCh: make(chan []*types.Header, 1),
}
go dl.qosTuner()
return dl
}
// Progress retrieves the synchronisation boundaries, specifically the origin
@ -247,6 +253,8 @@ func (d *Downloader) RegisterPeer(id string, version int, head common.Hash,
glog.V(logger.Error).Infoln("Register failed:", err)
return err
}
d.qosReduceConfidence()
return nil
}
@ -915,7 +923,7 @@ func (d *Downloader) fetchBlocks61(from uint64) error {
// Reserve a chunk of hashes for a peer. A nil can mean either that
// no more hashes are available, or that the peer is known not to
// have them.
request := d.queue.ReserveBlocks(peer, peer.BlockCapacity())
request := d.queue.ReserveBlocks(peer, peer.BlockCapacity(blockTargetRTT))
if request == nil {
continue
}
@ -956,7 +964,7 @@ func (d *Downloader) fetchHeight(p *peer) (*types.Header, error) {
// Request the advertised remote head block and wait for the response
go p.getRelHeaders(p.head, 1, 0, false)
timeout := time.After(headerTTL)
timeout := time.After(d.requestTTL())
for {
select {
case <-d.cancelCh:
@ -1024,7 +1032,7 @@ func (d *Downloader) findAncestor(p *peer, height uint64) (uint64, error) {
// Wait for the remote response to the head fetch
number, hash := uint64(0), common.Hash{}
timeout := time.After(hashTTL)
timeout := time.After(d.requestTTL())
for finished := false; !finished; {
select {
@ -1101,7 +1109,7 @@ func (d *Downloader) findAncestor(p *peer, height uint64) (uint64, error) {
// Split our chain interval in two, and request the hash to cross check
check := (start + end) / 2
timeout := time.After(hashTTL)
timeout := time.After(d.requestTTL())
go p.getAbsHeaders(uint64(check), 1, 0, false)
// Wait until a reply arrives to this request
@ -1182,7 +1190,7 @@ func (d *Downloader) fetchHeaders(p *peer, from uint64) error {
getHeaders := func(from uint64) {
request = time.Now()
timeout.Reset(headerTTL)
timeout.Reset(d.requestTTL())
if skeleton {
glog.V(logger.Detail).Infof("%v: fetching %d skeleton headers from #%d", p, MaxHeaderFetch, from)
@ -1290,13 +1298,13 @@ func (d *Downloader) fillHeaderSkeleton(from uint64, skeleton []*types.Header) (
pack := packet.(*headerPack)
return d.queue.DeliverHeaders(pack.peerId, pack.headers, d.headerProcCh)
}
expire = func() map[string]int { return d.queue.ExpireHeaders(headerTTL) }
expire = func() map[string]int { return d.queue.ExpireHeaders(d.requestTTL()) }
throttle = func() bool { return false }
reserve = func(p *peer, count int) (*fetchRequest, bool, error) {
return d.queue.ReserveHeaders(p, count), false, nil
}
fetch = func(p *peer, req *fetchRequest) error { return p.FetchHeaders(req.From, MaxHeaderFetch) }
capacity = func(p *peer) int { return p.HeaderCapacity() }
capacity = func(p *peer) int { return p.HeaderCapacity(d.requestRTT()) }
setIdle = func(p *peer, accepted int) { p.SetHeadersIdle(accepted) }
)
err := d.fetchParts(errCancelHeaderFetch, d.headerCh, deliver, d.queue.headerContCh, expire,
@ -1320,9 +1328,9 @@ func (d *Downloader) fetchBodies(from uint64) error {
pack := packet.(*bodyPack)
return d.queue.DeliverBodies(pack.peerId, pack.transactions, pack.uncles)
}
expire = func() map[string]int { return d.queue.ExpireBodies(bodyTTL) }
expire = func() map[string]int { return d.queue.ExpireBodies(d.requestTTL()) }
fetch = func(p *peer, req *fetchRequest) error { return p.FetchBodies(req) }
capacity = func(p *peer) int { return p.BlockCapacity() }
capacity = func(p *peer) int { return p.BlockCapacity(d.requestRTT()) }
setIdle = func(p *peer, accepted int) { p.SetBodiesIdle(accepted) }
)
err := d.fetchParts(errCancelBodyFetch, d.bodyCh, deliver, d.bodyWakeCh, expire,
@ -1344,9 +1352,9 @@ func (d *Downloader) fetchReceipts(from uint64) error {
pack := packet.(*receiptPack)
return d.queue.DeliverReceipts(pack.peerId, pack.receipts)
}
expire = func() map[string]int { return d.queue.ExpireReceipts(receiptTTL) }
expire = func() map[string]int { return d.queue.ExpireReceipts(d.requestTTL()) }
fetch = func(p *peer, req *fetchRequest) error { return p.FetchReceipts(req) }
capacity = func(p *peer) int { return p.ReceiptCapacity() }
capacity = func(p *peer) int { return p.ReceiptCapacity(d.requestRTT()) }
setIdle = func(p *peer, accepted int) { p.SetReceiptsIdle(accepted) }
)
err := d.fetchParts(errCancelReceiptFetch, d.receiptCh, deliver, d.receiptWakeCh, expire,
@ -1396,13 +1404,13 @@ func (d *Downloader) fetchNodeData() error {
}
})
}
expire = func() map[string]int { return d.queue.ExpireNodeData(stateTTL) }
expire = func() map[string]int { return d.queue.ExpireNodeData(d.requestTTL()) }
throttle = func() bool { return false }
reserve = func(p *peer, count int) (*fetchRequest, bool, error) {
return d.queue.ReserveNodeData(p, count), false, nil
}
fetch = func(p *peer, req *fetchRequest) error { return p.FetchNodeData(req) }
capacity = func(p *peer) int { return p.NodeDataCapacity() }
capacity = func(p *peer) int { return p.NodeDataCapacity(d.requestRTT()) }
setIdle = func(p *peer, accepted int) { p.SetNodeDataIdle(accepted) }
)
err := d.fetchParts(errCancelStateFetch, d.stateCh, deliver, d.stateWakeCh, expire,
@ -1864,3 +1872,82 @@ func (d *Downloader) deliver(id string, destCh chan dataPack, packet dataPack, i
return errNoSyncActive
}
}
// qosTuner is the quality of service tuning loop that occasionally gathers the
// peer latency statistics and updates the estimated request round trip time.
func (d *Downloader) qosTuner() {
for atomic.LoadInt32(&d.interrupt) == 0 {
// Gather all the active RTTs and set the target RTT to the median
rtts := d.peers.RTTs()
var rtt time.Duration
if qosTuningPeers <= len(rtts) {
rtt = rtts[qosTuningPeers/2] // Median of our tuning peers
} else if len(rtts) > 0 {
rtt = rtts[len(rtts)/2] // Median of our connected peers (maintain even like this some baseline qos)
} else {
rtt = rttMaxEstimate // No peers, reset to some sane default
}
if rtt < rttMinEstimate {
rtt = rttMinEstimate
}
if rtt > rttMaxEstimate {
rtt = rttMaxEstimate
}
rtt = time.Duration(float64(1-qosTuningImpact)*float64(atomic.LoadUint64(&d.rttEstimate)) + qosTuningImpact*float64(rtt))
atomic.StoreUint64(&d.rttEstimate, uint64(rtt))
// A new RTT cycle passed, increase our confidence in the estimated RTT
conf := atomic.LoadUint64(&d.rttConfidence)
conf = conf + (1000000-conf)/2
atomic.StoreUint64(&d.rttConfidence, conf)
// Log the new QoS values and sleep until the next RTT
glog.V(logger.Debug).Infof("quality of service: rtt %v, conf %.3f, ttl %v", rtt, float64(conf)/1000000.0, d.requestTTL())
time.Sleep(rtt)
}
}
// qosReduceConfidence is meant to be called when a new peer joins the downloader's
// peer set, needing to reduce the confidence we have in out QoS estimates.
func (d *Downloader) qosReduceConfidence() {
// If we have a single peer, confidence is always 1
peers := uint64(d.peers.Len())
if peers == 1 {
atomic.StoreUint64(&d.rttConfidence, 1000000)
return
}
// If we have a ton of peers, don't drop confidence)
if peers >= uint64(qosConfidenceCap) {
return
}
// Otherwise drop the confidence factor
conf := atomic.LoadUint64(&d.rttConfidence) * (peers - 1) / peers
if float64(conf)/1000000 < rttMinConfidence {
conf = uint64(rttMinConfidence * 1000000)
}
atomic.StoreUint64(&d.rttConfidence, conf)
rtt := time.Duration(atomic.LoadUint64(&d.rttEstimate))
glog.V(logger.Debug).Infof("quality of service: rtt %v, conf %.3f, ttl %v", rtt, float64(conf)/1000000.0, d.requestTTL())
}
// requestRTT returns the current target round trip time for a download request
// to complete in.
//
// Note, the returned RTT is .9 of the actually estimated RTT. The reason is that
// the downloader tries to adapt queries to the RTT, so multiple RTT values can
// be adapted to, but smaller ones are preffered (stabler download stream).
func (d *Downloader) requestRTT() time.Duration {
return time.Duration(atomic.LoadUint64(&d.rttEstimate)) * 9 / 10
}
// requestTTL returns the current timeout allowance for a single download request
// to finish under.
func (d *Downloader) requestTTL() time.Duration {
var (
rtt = time.Duration(atomic.LoadUint64(&d.rttEstimate))
conf = float64(atomic.LoadUint64(&d.rttConfidence)) / 1000000.0
)
return time.Duration(rttTTLScaling) * time.Duration(float64(rtt)/conf)
}

2
eth/downloader/downloader_test.go
View file

@ -1734,7 +1734,7 @@ func testDeliverHeadersHang(t *testing.T, protocol int, mode SyncMode) {
impl := tester.peerGetAbsHeadersFn("peer", 0)
go impl(from, count, skip, reverse)
// None of the extra deliveries should block.
timeout := time.After(5 * time.Second)
timeout := time.After(15 * time.Second)
for i := 0; i < cap(deliveriesDone); i++ {
select {
case <-deliveriesDone:

65
eth/downloader/peer.go
View file

@ -31,8 +31,8 @@ import (
)
const (
maxLackingHashes = 4096 // Maximum number of entries allowed on the list or lacking items
throughputImpact = 0.1 // The impact a single measurement has on a peer's final throughput value.
maxLackingHashes = 4096 // Maximum number of entries allowed on the list or lacking items
measurementImpact = 0.1 // The impact a single measurement has on a peer's final throughput value.
)
// Hash and block fetchers belonging to eth/61 and below
@ -68,6 +68,8 @@ type peer struct {
receiptThroughput float64 // Number of receipts measured to be retrievable per second
stateThroughput float64 // Number of node data pieces measured to be retrievable per second
rtt time.Duration // Request round trip time to track responsiveness (QoS)
headerStarted time.Time // Time instance when the last header fetch was started
blockStarted time.Time // Time instance when the last block (body) fetch was started
receiptStarted time.Time // Time instance when the last receipt fetch was started
@ -290,44 +292,47 @@ func (p *peer) setIdle(started time.Time, delivered int, throughput *float64, id
return
}
// Otherwise update the throughput with a new measurement
measured := float64(delivered) / (float64(time.Since(started)+1) / float64(time.Second)) // +1 (ns) to ensure non-zero divisor
*throughput = (1-throughputImpact)*(*throughput) + throughputImpact*measured
elapsed := time.Since(started) + 1 // +1 (ns) to ensure non-zero divisor
measured := float64(delivered) / (float64(elapsed) / float64(time.Second))
*throughput = (1-measurementImpact)*(*throughput) + measurementImpact*measured
p.rtt = time.Duration((1-measurementImpact)*float64(p.rtt) + measurementImpact*float64(elapsed))
}
// HeaderCapacity retrieves the peers header download allowance based on its
// previously discovered throughput.
func (p *peer) HeaderCapacity() int {
func (p *peer) HeaderCapacity(targetRTT time.Duration) int {
p.lock.RLock()
defer p.lock.RUnlock()
return int(math.Max(1, math.Min(p.headerThroughput*float64(headerTargetRTT)/float64(time.Second), float64(MaxHeaderFetch))))
return int(math.Min(1+math.Max(1, p.headerThroughput*float64(targetRTT)/float64(time.Second)), float64(MaxHeaderFetch)))
}
// BlockCapacity retrieves the peers block download allowance based on its
// previously discovered throughput.
func (p *peer) BlockCapacity() int {
func (p *peer) BlockCapacity(targetRTT time.Duration) int {
p.lock.RLock()
defer p.lock.RUnlock()
return int(math.Max(1, math.Min(p.blockThroughput*float64(blockTargetRTT)/float64(time.Second), float64(MaxBlockFetch))))
return int(math.Min(1+math.Max(1, p.blockThroughput*float64(targetRTT)/float64(time.Second)), float64(MaxBlockFetch)))
}
// ReceiptCapacity retrieves the peers receipt download allowance based on its
// previously discovered throughput.
func (p *peer) ReceiptCapacity() int {
func (p *peer) ReceiptCapacity(targetRTT time.Duration) int {
p.lock.RLock()
defer p.lock.RUnlock()
return int(math.Max(1, math.Min(p.receiptThroughput*float64(receiptTargetRTT)/float64(time.Second), float64(MaxReceiptFetch))))
return int(math.Min(1+math.Max(1, p.receiptThroughput*float64(targetRTT)/float64(time.Second)), float64(MaxReceiptFetch)))
}
// NodeDataCapacity retrieves the peers state download allowance based on its
// previously discovered throughput.
func (p *peer) NodeDataCapacity() int {
func (p *peer) NodeDataCapacity(targetRTT time.Duration) int {
p.lock.RLock()
defer p.lock.RUnlock()
return int(math.Max(1, math.Min(p.stateThroughput*float64(stateTargetRTT)/float64(time.Second), float64(MaxStateFetch))))
return int(math.Min(1+math.Max(1, p.stateThroughput*float64(targetRTT)/float64(time.Second)), float64(MaxStateFetch)))
}
// MarkLacking appends a new entity to the set of items (blocks, receipts, states)
@ -362,11 +367,12 @@ func (p *peer) String() string {
defer p.lock.RUnlock()
return fmt.Sprintf("Peer %s [%s]", p.id,
fmt.Sprintf("headers %3.2f/s, ", p.headerThroughput)+
fmt.Sprintf("blocks %3.2f/s, ", p.blockThroughput)+
fmt.Sprintf("receipts %3.2f/s, ", p.receiptThroughput)+
fmt.Sprintf("states %3.2f/s, ", p.stateThroughput)+
fmt.Sprintf("lacking %4d", len(p.lacking)),
fmt.Sprintf("hs %3.2f/s, ", p.headerThroughput)+
fmt.Sprintf("bs %3.2f/s, ", p.blockThroughput)+
fmt.Sprintf("rs %3.2f/s, ", p.receiptThroughput)+
fmt.Sprintf("ss %3.2f/s, ", p.stateThroughput)+
fmt.Sprintf("miss %4d, ", len(p.lacking))+
fmt.Sprintf("rtt %v", p.rtt),
)
}
@ -410,6 +416,7 @@ func (ps *peerSet) Register(p *peer) error {
}
if len(ps.peers) > 0 {
p.headerThroughput, p.blockThroughput, p.receiptThroughput, p.stateThroughput = 0, 0, 0, 0
p.rtt = rttMaxEstimate
for _, peer := range ps.peers {
peer.lock.RLock()
@ -564,3 +571,27 @@ func (ps *peerSet) idlePeers(minProtocol, maxProtocol int, idleCheck func(*peer)
}
return idle, total
}
// RTTs retrieves all the round trip times measured for the current set of peers,
// sorted ascending.
func (ps *peerSet) RTTs() []time.Duration {
// Gather all the currnetly measured round trip times
ps.lock.RLock()
defer ps.lock.RUnlock()
rtts := make([]time.Duration, 0, len(ps.peers))
for _, p := range ps.peers {
p.lock.RLock()
rtts = append(rtts, p.rtt)
p.lock.RUnlock()
}
// Sort into ascending order and return them
for i := 0; i < len(rtts); i++ {
for j := i + 1; j < len(rtts); j++ {
if rtts[i] > rtts[j] {
rtts[i], rtts[j] = rtts[j], rtts[i]
}
}
}
return rtts
}