Base-Case Experiment: One flow vs Two flows, 64KB of buffering, Utilization/Drop/FCT No congestion Congestion 300 paced Bottleneck Link Utilization (Mbps) non − paced 250 200 38% 150 100 50 0 0 50 100 150 200 250 300 Time (sec) 1 1 paced paced 0.9 0.9 non − paced non − paced 0.8 0.8 0.7 0.7 1RTT 0.6 0.6 CDF CDF 0.5 0.5 2RTTs 2RTTs 0.4 0.4 0.3 0.3 0.2 0.2 0.1 0.1 0 0 0.039 0.063 0.1 0.2 0.3 0.4 0.06 0.2 0.5 1 2 3 5 7 9 Flow Completion Time (sec) Flow Completion Time (sec)
Multiple flows: Link Utilization/Drop/Latency Buffer size 1.7% of BDP , varying number of flows 10
Multiple flows: Link Utilization/Drop/Latency Buffer size 1.7% of BDP , varying number of flows N * PoI Bottleneck Link Utilization (Mbps) 1000 800 600 400 paced 200 non − paced 0 0 10 20 30 40 50 60 70 80 90 100 Number of Flows 10
Multiple flows: Link Utilization/Drop/Latency Buffer size 1.7% of BDP , varying number of flows N * PoI Bottleneck Link Utilization (Mbps) 1000 800 600 400 paced 200 non − paced 0 0 10 20 30 40 50 60 70 80 90 100 Number of Flows N * PoI 1 paced Bottleneck Link Drop (%) non − paced 0.8 0.6 0.4 0.2 0 0 10 20 30 40 50 60 70 80 90 100 10 Number of Flows
Multiple flows: Link Utilization/Drop/Latency Buffer size 1.7% of BDP , varying number of flows N * N * PoI PoI Bottleneck Link Utilization (Mbps) 1000 1 paced non − paced 0.8 800 Average FCT (sec) 600 0.6 400 0.4 paced 200 0.2 non − paced 0 0 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 Number of Flows Number of Flows N * PoI 1 paced Bottleneck Link Drop (%) non − paced 0.8 0.6 0.4 0.2 0 0 10 20 30 40 50 60 70 80 90 100 10 Number of Flows
Multiple flows: Link Utilization/Drop/Latency Buffer size 1.7% of BDP , varying number of flows N * N * PoI PoI Bottleneck Link Utilization (Mbps) 1000 1 paced non − paced 0.8 800 Average FCT (sec) 600 0.6 400 0.4 paced 200 0.2 non − paced 0 0 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 Number of Flows Number of Flows N * N * PoI PoI 1 2 paced paced 99 th Percentile FCT (sec) 1.8 Bottleneck Link Drop (%) non − paced non − paced 0.8 1.6 1.4 0.6 1.2 1 0.4 0.8 0.6 0.2 0.4 0.2 0 0 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 10 Number of Flows Number of Flows
Multiple flows: Link Utilization/Drop/Latency Buffer size 1.7% of BDP , varying number of flows N * N * PoI PoI Bottleneck Link Utilization (Mbps) 1000 1 paced non − paced 0.8 800 Average FCT (sec) 600 0.6 400 0.4 paced 200 0.2 non − paced 0 0 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 • Number of concurrent connections increase beyond a Number of Flows Number of Flows N * N * certain point the benefits of pacing diminish. PoI PoI 1 2 paced paced 99 th Percentile FCT (sec) 1.8 Bottleneck Link Drop (%) non − paced non − paced 0.8 1.6 1.4 0.6 1.2 1 0.4 0.8 0.6 0.2 0.4 0.2 0 0 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 10 Number of Flows Number of Flows
Multiple flows: Link Utilization/Drop/Latency Buffer size 3.4% of BDP , varying number of flows 11
Multiple flows: Link Utilization/Drop/Latency Buffer size 3.4% of BDP , varying number of flows N * N * PoI PoI Bottleneck Link Utilization (Mbps) 1 1000 800 0.8 Average FCT (sec) 600 0.6 400 0.4 200 paced paced 0.2 non − paced non − paced 0 0 10 20 30 40 50 60 70 80 90 100 0 Number of Flows 0 10 20 30 40 50 60 70 80 90 100 Number of Flows N * PoI 0.8 2 paced nonpaced 99 th Percentile FCT (sec) 1.8 0.7 1.6 0.6 Bottleneck link drop(%) 1.4 0.5 1.2 0.4 1 0.8 0.3 0.6 paced 0.2 0.4 non − paced 0.1 0.2 0 0 0 20 40 60 80 100 0 10 20 30 40 50 60 70 80 90 100 11 Number of flows sharing the bottleneck Number of Flows
Multiple flows: Link Utilization/Drop/Latency Buffer size 3.4% of BDP , varying number of flows N * N * PoI PoI Bottleneck Link Utilization (Mbps) 1 1000 800 0.8 Average FCT (sec) 600 • Aagarwal et al.: Don’t pace! 0.6 400 • 50 flows, BDP 1250 packets and buffer size 0.4 200 paced 312 packets paced 0.2 non − paced non − paced 0 • N* = 8 flows. 0 10 20 30 40 50 60 70 80 90 100 0 Number of Flows 0 10 20 30 40 50 60 70 80 90 100 • Kulik et al.: Pace! Number of Flows N * PoI 0.8 2 • 1 flow, BDP 91 packets, buffer size 10 paced nonpaced 99 th Percentile FCT (sec) 1.8 0.7 1.6 packets. 0.6 Bottleneck link drop(%) 1.4 0.5 • N* = 9 flows. 1.2 0.4 1 0.8 0.3 0.6 paced 0.2 0.4 non − paced 0.1 0.2 0 0 0 20 40 60 80 100 0 10 20 30 40 50 60 70 80 90 100 11 Number of flows sharing the bottleneck Number of Flows
N* vs. Bu fg er 12
N* vs. Bu fg er Bottleneck Link Utilization (Mbps) 1000 800 600 400 200 paced non − paced 0 50 100 150 200 250 Buffer Size (KB) 12
N* vs. Bu fg er Bottleneck Link Utilization (Mbps) 1000 800 600 400 200 paced non − paced 0 50 100 150 200 250 Buffer Size (KB) 0.8 paced nonpaced 0.7 0.6 Bottleneck link drop(%) 0.5 0.4 0.3 0.2 0.1 0 50 100 150 200 250 12 Buffer size(KB)
N* vs. Bu fg er Bottleneck Link Utilization (Mbps) 1.4 1000 paced 1.2 non − paced 800 CT (sec) 1 600 0.8 Average � 0.6 400 0.4 200 paced 0.2 non − paced 0 0 50 100 150 200 250 50 100 150 200 250 Buffer Size (KB) Buffer Size (KB) 0.8 paced nonpaced 0.7 0.6 Bottleneck link drop(%) 0.5 0.4 0.3 0.2 0.1 0 50 100 150 200 250 12 Buffer size(KB)
N* vs. Bu fg er Bottleneck Link Utilization (Mbps) 1.4 1000 paced 1.2 non − paced 800 CT (sec) 1 600 0.8 Average � 0.6 400 0.4 200 paced 0.2 non − paced 0 0 50 100 150 200 250 50 100 150 200 250 Buffer Size (KB) Buffer Size (KB) 2.8 0.8 paced paced CT (sec) nonpaced 2.4 0.7 non − paced 0.6 2 Bottleneck link drop(%) 99 th Percentile � 0.5 1.6 0.4 1.2 0.3 0.8 0.2 0.4 0.1 0 0 50 100 150 200 250 50 100 150 200 250 12 Buffer size(KB) Buffer Size (KB)
N* vs. Bu fg er Bottleneck Link Utilization (Mbps) 1.4 1000 paced 1.2 non − paced 800 CT (sec) 1 600 0.8 Average � 0.6 400 0.4 200 paced 0.2 non − paced 0 0 50 100 150 200 250 50 100 150 200 250 Buffer Size (KB) Buffer Size (KB) 2.8 0.8 paced paced CT (sec) nonpaced 2.4 0.7 non − paced 0.6 2 Bottleneck link drop(%) 99 th Percentile � 0.5 1.6 0.4 1.2 0.3 0.8 0.2 0.4 0.1 0 0 50 100 150 200 250 50 100 150 200 250 12 Buffer size(KB) Buffer Size (KB)
Clustering Effect: The probability of packets from a flow being followed by packets from other flows 13
Clustering Effect: The probability of packets from a flow being followed by packets from other flows Non-paced: Packets of each flow are clustered together. 13
Clustering Effect: The probability of packets from a flow being followed by packets from other flows Non-paced: Packets of each flow Paced: Packets of different flows are are clustered together. multiplexed. 13
Drop Synchronization: Number of Flows Affected by Drop Event 14
Drop Synchronization: Number of Flows Affected by Drop Event NetFPGA router to count the number of flows affected by drop events. 14
Drop Synchronization: Number of Flows Affected by Drop Event NetFPGA router to count the number of flows affected by drop events. 1 1 1 paced 0.9 0.9 paced paced 0.9 non − paced 0.8 0.8 0.8 non − paced non − paced 0.7 0.7 0.7 0.6 0.6 0.6 CDF CDF CDF 0.5 0.5 0.5 0.4 0.4 0.4 0.3 0.3 0.3 0.2 0.2 0.2 0.1 0.1 0.1 0 0 0 0 20 40 60 80 0 50 100 150 200 250 300 350 400 0 10 20 30 40 Number of Flows Affected by Drop Event Number of Flows Affected by Drop Event Number of Flows Affected by Drop Event N: 48 N: 96 N: 384 14
Drop Synchronization: Number of Flows Affected by Drop Event NetFPGA router to count the number of flows affected by drop events. 1 1 1 paced 0.9 0.9 paced paced 0.9 non − paced 0.8 0.8 0.8 non − paced non − paced 0.7 0.7 0.7 0.6 0.6 0.6 CDF CDF CDF 0.5 0.5 0.5 0.4 0.4 0.4 0.3 0.3 0.3 0.2 0.2 0.2 0.1 0.1 0.1 0 0 0 0 20 40 60 80 0 50 100 150 200 250 300 350 400 0 10 20 30 40 Number of Flows Affected by Drop Event Number of Flows Affected by Drop Event Number of Flows Affected by Drop Event N: 48 N: 96 N: 384 14
Future Trends for Pacing: per-egress pacing. 15
Future Trends for Pacing: per-egress pacing. N * N * PoI PoI Bottleneck Link Utilization (Mbps) 1 1000 per − flow paced non − paced Average RCT (sec) 0.8 800 per − host + per − flow paced 0.6 600 0.4 400 per − flow paced 200 0.2 non − paced per − host + per − flow paced 0 0 6 12 24 48 96 192 6 12 24 48 96 192 Number of Flows Number of Flows N * PoI 20 per − flow paced 2.2 per − flow paced nonpaced 99 th Percentile RCT (sec) 2 per − host + per − flow paced non − paced Bottleneck Link Drop (%) 1.8 15 per − host + per − flow paced 1.6 1.4 1.2 10 1 0.8 0.6 5 0.4 0.2 0 0 6 12 24 48 96 192 6 12 24 48 96 192 Number of flows Number of Flows 15
Future Trends for Pacing: per-egress pacing. N * N * PoI PoI Bottleneck Link Utilization (Mbps) 1 1000 per − flow paced non − paced Average RCT (sec) 0.8 800 per − host + per − flow paced 0.6 600 0.4 400 per − flow paced 200 0.2 non − paced per − host + per − flow paced 0 0 6 12 24 48 96 192 6 12 24 48 96 192 Number of Flows Number of Flows N * PoI 20 per − flow paced 2.2 per − flow paced nonpaced 99 th Percentile RCT (sec) 2 per − host + per − flow paced non − paced Bottleneck Link Drop (%) 1.8 15 per − host + per − flow paced 1.6 1.4 1.2 10 1 0.8 0.6 5 0.4 0.2 0 0 6 12 24 48 96 192 6 12 24 48 96 192 Number of flows Number of Flows 15
Future Trends for Pacing: per-egress pacing. N * N * PoI PoI Bottleneck Link Utilization (Mbps) 1 1000 per − flow paced non − paced Average RCT (sec) 0.8 800 per − host + per − flow paced 0.6 600 0.4 400 per − flow paced 200 0.2 non − paced per − host + per − flow paced 0 0 6 12 24 48 96 192 6 12 24 48 96 192 Number of Flows Number of Flows N * PoI 20 per − flow paced 2.2 per − flow paced nonpaced 99 th Percentile RCT (sec) 2 per − host + per − flow paced non − paced Bottleneck Link Drop (%) 1.8 15 per − host + per − flow paced 1.6 1.4 1.2 10 1 0.8 0.6 5 0.4 0.2 0 0 6 12 24 48 96 192 6 12 24 48 96 192 Number of flows Number of Flows 15
Future Trends for Pacing: per-egress pacing. N * N * PoI PoI Bottleneck Link Utilization (Mbps) 1 1000 per − flow paced non − paced Average RCT (sec) 0.8 800 per − host + per − flow paced 0.6 600 0.4 400 per − flow paced 200 0.2 non − paced per − host + per − flow paced 0 0 6 12 24 48 96 192 6 12 24 48 96 192 Number of Flows Number of Flows N * PoI 20 per − flow paced 2.2 per − flow paced nonpaced 99 th Percentile RCT (sec) 2 per − host + per − flow paced non − paced Bottleneck Link Drop (%) 1.8 15 per − host + per − flow paced 1.6 1.4 1.2 10 1 0.8 0.6 5 0.4 0.2 0 0 6 12 24 48 96 192 6 12 24 48 96 192 Number of flows Number of Flows 15
Future Trends for Pacing: per-egress pacing. N * N * PoI PoI Bottleneck Link Utilization (Mbps) 1 1000 per − flow paced non − paced Average RCT (sec) 0.8 800 per − host + per − flow paced 0.6 600 0.4 400 per − flow paced 200 0.2 non − paced per − host + per − flow paced 0 0 6 12 24 48 96 192 6 12 24 48 96 192 Number of Flows Number of Flows N * PoI 20 per − flow paced 2.2 per − flow paced nonpaced 99 th Percentile RCT (sec) 2 per − host + per − flow paced non − paced Bottleneck Link Drop (%) 1.8 15 per − host + per − flow paced 1.6 1.4 1.2 10 1 0.8 0.6 5 0.4 0.2 0 0 6 12 24 48 96 192 6 12 24 48 96 192 Number of flows Number of Flows 15
Conclusions and Future work ๏ Re-examine TCP pacing’s effectiveness: ๏ Demonstrate when TCP pacing brings benefits in such environments. ๏ Inter-flow burstiness ๏ Burst-pacing vs. packet-pacing. ๏ Per-egress pacing. 16
Renewed Interest 17
Tra ffj c Burstiness Survey ๏ ‘Bursty’ is a word with no agreed meaning. How do you define a bursty traffic? ๏ If you are involved with a data center, is your data center traffic bursty? ๏ If yes, do you think that it will be useful to supress the burstiness in your traffic? ๏ If no, are you already supressing the burstiness? How? Would you anticipate the traffic becoming burstier in the future? monia@cs.toronto.edu 18
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Base-Case Experiment: One RPC vs Two RPCs, 64KB of bu fg ering, Latency 20
Multiple flows: Link Utilization/Drop/ Latency Bu fg er size: 6% of BDP, varying number of 21
Base-Case Experiment: One RPC vs Two RPCs, 64KB of bu fg ering, Latency / Queue Occupancy 22
Base-Case Experiment: One RPC vs Two RPCs, 64KB of bu fg ering, Latency / Queue Occupancy 22
Base-Case Experiment: One RPC vs Two RPCs, 64KB of bu fg ering, Latency / Queue Occupancy 22
Base-Case Experiment: One RPC vs Two RPCs, 64KB of bu fg ering, Latency / Queue Occupancy 22
Functional test 23
Functional test 23
Functional test 23
Functional test 23
RPC vs. Streaming Paced by ack clocking Bursty 10GE 1GE 10GE RTT = 10ms 24
Zooming in more on the paced flow 25
Multiple flows: Link Utilization/Drop/Latency Buffer size 6.8% of BDP , varying number of flows 26
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