ECM and E 2 CM performance w/ BCN(0,0) Single-Hop High Degree Hotspot Cyriel Minkenberg & Mitch Gusat IBM Research GmbH, Zurich May 3, 2007
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
ECM and E2CM performance w/ BCN(0,0)
Single-Hop High Degree Hotspot
Cyriel Minkenberg & Mitch GusatIBM Research GmbH, Zurich
May 3, 2007
IBM Research GmbH, Zurich 2
Targets
1. Study Output-Generated (OG) single-hop withhigh hotspot degree (HSD) congestion
2. Test the impact of BCN(0,0)
Conditions, parameters, simulation environment• Traffic: i.i.d. Bernoulli arrivals• LL-FC: runs with and w/o PAUSE• CM: No CM, ECM, E2CM, E2CM-CP
– With/without BCN(0,0)• Metrics: TPaggr, TPhot, Qhot, frame drops
• for details see the “fine print” page
IBM Research GmbH, Zurich 3
Output-Generated Single-Hop High HSD
• All nodes: Uniform destination distribution, load = 85% (8.5 Gb/s)• Node 1 service rate = 10%• One congestion point
– Hotspot degree = N-1– All flows affected
Node 2
Node 1
Service rate = 10%Service rate = 10%
85%85%
CoreCoreSwitchSwitch
85%85%Node N
85%85%N= {16,32,64,128,256}
IBM Research GmbH, Zurich 4
Simulation Setup & Parameters (same as before)• Traffic
– I.i.d. Bernoulli arrivals, geometrically distributed burst size around mean B
– Uniform destination distribution (to all nodes except self)
– Fixed frame size = 1500 B
• Scenario1. Single-hop output-generated hotspot
• Switch– Radix N = [8, 16, 32, 64, 128, 256]– M = 300 KB/port– Partitioned memory per input, shared among all
outputs– No limit on per-output memory usage– PAUSE enabled or disabled
• Applied on a per input basis based on local high/low watermarks
• watermarkhigh = 260 KB• watermarklow = 230 KB• If disabled, frames dropped when input
partition full
• Adapter– Per-node virtual output queuing, round-robin
scheduling– No limit on number of rate limiters– Ingress buffer size = 1500 KB, partitioned across
VOQs, per-flow selective source quench used when VOQ full, round-robin VOQ service
– Egress buffer size = 150 KB– PAUSE enabled
• watermarkhigh = 150 – rtt*bw KB• watermarklow = watermarkhigh - 10 KB
• ECM– W = 2.0– Qeq = 75 KB (= M/4)– Gd = 0.5 / ((2*W+1)*Qeq)– Gi0 = (Rlink / Runit) * ((2*W+1)*Qeq)– Gi = 0.1 * Gi0– Psample = 2% (on average 1 sample every 75 KB– Runit = Rmin = 1 Mb/s– BCN_MAX enabled, threshold = 260 KB– BCN(0,0) dis/enabled, threshold = 1040 KB
• E2CM (per-flow)– W = 2.0– Qeq,flow = 15 KB– Gd, flow = 0.5 / ((2*W+1)*Qeq,flow)– Gi, flow = 0.005 * (Rlink / Runit) / ((2*W+1)*Qeq,flow)– Psample = 2% (on average 1 sample every 75 KB)– Runit = Rmin = 1 Mb/s– BCN_MAX enabled, threshold = 52 KB– BCN(0,0) dis/enabled, threshold = 208 KB
E2CM-CP = E2CM with continuous probing, i.e., probing
is always active
IBM Research GmbH, Zurich 5
Aggregate throughput: no BCN(0,0), PAUSE disabledECMNo CM
E2CM E2CM-CP
IBM Research GmbH, Zurich 6
Aggregate throughput: no BCN(0,0), PAUSE enabledECMNo CM
E2CM E2CM-CP
IBM Research GmbH, Zurich 7
Hot port throughput: no BCN(0,0), PAUSE disabledECMNo CM
E2CM E2CM-CP
IBM Research GmbH, Zurich 8
Hot port throughput: no BCN(0,0), PAUSE enabledECMNo CM
E2CM E2CM-CP
IBM Research GmbH, Zurich 9
Hot queue length: no BCN(0,0), PAUSE disabledECMNo CM
E2CM E2CM-CP
IBM Research GmbH, Zurich 10
Hot queue length: no BCN(0,0), PAUSE enabledECMNo CM
E2CM E2CM-CP
IBM Research GmbH, Zurich 11
Frame drops: no BCN(0,0), PAUSE disabled
100
1000
10000
100000
1000000
10000000
100000000
No CM ECM E2CM E2CM-CP
Congestion Management Scheme
Num
ber
of fr
ames
dro
pped
8163264128256
IBM Research GmbH, Zurich 12
Simulation results w/ BCN(0,0)
IBM Research GmbH, Zurich 13
Aggregate throughput: w/ BCN(0,0), PAUSE disabledECMNo CM
E2CM E2CM-CP
IBM Research GmbH, Zurich 14
Aggregate throughput: w/ BCN(0,0), PAUSE enabledECMNo CM
E2CM E2CM-CP
IBM Research GmbH, Zurich 15
Hot port throughput: w/ BCN(0,0), PAUSE disabledECMNo CM
E2CM E2CM-CP
IBM Research GmbH, Zurich 16
Hot port throughput: w/ BCN(0,0), PAUSE enabledECMNo CM
E2CM E2CM-CP
IBM Research GmbH, Zurich 17
Hot queue length: w/ BCN(0,0), PAUSE disabledECMNo CM
E2CM E2CM-CP
IBM Research GmbH, Zurich 18
Hot queue length: w/ BCN(0,0), PAUSE enabledECMNo CM
E2CM E2CM-CP
IBM Research GmbH, Zurich 19
Frame drops: w/ BCN(0,0), PAUSE disabled
100
1000
10000
100000
1000000
10000000
100000000
No CM ECM E2CM E2CM-CP
Congestion Management Scheme
Num
ber o
f fra
mes
dro
pped
8163264128256
IBM Research GmbH, Zurich 20
Conclusions on High-HSD OG w/ BCN(0,0)• Last week’s conclusions from here still apply
– Tough benchmark!– BCN_MAX is not sufficient to control this case
• BCN(0,0) provides major benefits in this case– No collapse of average throughput– Drastically reduced drop rates– Queue convergence even for large N– w/o having to retune the gains for such corner cases...
• Per-flow sampling (E2CM)– Improves recovery speed and stability
• However, ECM’s recovery timer is not implemented– Has difficulty coping with high hotspot degree
• E2CM’s Qeq,flow is not scaled down as N increases
IBM Research GmbH, Zurich 21
Backup
IBM Research GmbH, Zurich 22
Simulation duration per run
• Number of nodes x 2 simulation time x 2.5
2 37
16
40
102
0
20
40
60
80
100
120
8 16 32 64 128 256
Number of nodes
Sim
ulat
ion
dura
tion
(min
utes
)
IBM Research GmbH, Zurich 23
Comparative Impact of BCN(0,0) on Loss w/ PAUSE Disabled
100
1000
10000
100000
1000000
10000000
100000000
No CM ECM E2CM E2CM-CP
Congestion Management Scheme
Num
ber o
f fra
mes
dro
pped
8163264128256
100
1000
10000
100000
1000000
10000000
100000000
No CM ECM E2CM E2CM-CP
Congestion Management Scheme
Num
ber o
f fra
mes
dro
pped
8163264128256
Related Documents
