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A Survey on Parallel Computing in Heterogeneous Grid Environments. Takeshi Sekiya Chikayama-Taura Laboratory M1 Nov 24, 2006. Dynamic Change of CPU/Network Load. Parallel Computing in Grid Environments. Increase opportunity in which we can use multi cluster environments - PowerPoint PPT Presentation
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A Survey on Parallel Computing in Heterogeneous Grid Environments
Takeshi Sekiya
Chikayama-Taura Laboratory M1
Nov 24, 2006
Parallel Computingin Grid Environments• Increase opportunity in whic
h we can use multi cluster environments– But, schemes for stand alone c
lusters cause problems in grid-like usage
• New mechanisms are needed– Handling heterogeneity– Firewall/NAT traversal– Adaptation to dynamic environ
ment – Monitoring
Heterogeneous hardware and
software
Failure
Firewall/NAT
Maintenance
DynamicChange of
CPU/Network Load
Complex Configuration
Difficult to Know What’s Happening
Heterogeneous Environments
• Heterogeneous machines– Binaries are different– Complex configuration are required when
hardware/software is different
• Heterogeneous networks– Overheads of synchronization in parallel a
pplication with different latency/bandwidth– Firewalls/NATs
Firewall/NAT
• Firewalls/NATs hinder bi-directional connectivity
• Bi-directional TCP/IP connectivity needs to be provided to support a wide spectrum of applications
Firewall or NAT
Solutions to the Internet Asymmetric-Connectivity Problem
• MPI Environment on Grid with Virtual Machines [Tachibana et al. 2006]
– Xen for VM and VPN for Virtual Network– Low cost VM migration
• ViNe [Tsugawa et al. 2006]
– A host named Virtual Router– Overlay network base
• WOW [Ganguly et al. 2006]
Outline
• Introduction• WOW
– IPOP: IP over P2P– Routing IP on the P2P Overlay– Connection Setup– Joining an Existing Network– NAT Traversal– Experiments
• Summary
Objective and Approach
• The system architected to …– Adapt heterogeneous environments
• Present to end-users a cluster-like environment– Scale to large number of nodes– Facilitate the addition of nodes through self-
organization of virtual network• Less manual configuration
• Approach with Virtualization– Virtual Machines
• Homogeneous software– Self-organizing overlay network
• All-to-all connectivity
Virtual Machine
• A homogeneous software environment
• Offering opportunities for load balancing and fault tolerance
• Users can use pre-configured systems– Linux distribution– Libraries and softwares
Virtual Network
NAT
P2P overlay network
IPOP (IP over P2P)
Physical Infrastructure
P2P Network
Virtual Grid Cluster
firewall
IPOP [Ganguly et al. 2006]
• Characteristics– A virtual IP address space– Self-organizing
• Architecture– IP tunneling over P2P– A virtualized network interface (tap)
captures virtual IP packets– Brunet P2P overlay network
Capturing Virtual IP Packets
• The tap appears as a network interface from applications
• IPOP translates virtual IP addresses to Brunet P2P network addresses
IPOP
application
tap
IPOP
application
tap
Ethernet Frame
IP Packet
Brunet Message
IP Packet
Ethernet Frame
IP Packet
Tunneling
Brunet P2P
• Ring-structured overlay • Organized connections
– Near: with neighbors– Far: across the ring
• 160 bit SHA-1 hash address
• Greedy routing• Each node has constant
number of connections– O(log2(n)) overlay hops
n1
n2
n3n4
n5
n6
n7
n8
n9n10
n11
n12
Multi hop pathfrom n1 to n7
Connection SetupConnection Protocol
• Node A wishes to connect to node B1. A sends a CTM (Connect
To Me) request to B over P2P network• The CTM request contains
A’s URI
2. When B receives the CTM request, B sends a CTM reply to A• The CTM reply contains B’s
URI
AB
CTM requestCTM reply
URI (Uniform Resource Indicator)ex.) brunet.tcp:192.0.0.1:1024
Connection SetupLinking Protocol
AB
3. B sends a link request message to A over the physical network
4. When A receives the link request, A simply responds with a link reply message
5. Finally, new connection is established between A and B
link request
link reply
Direct connectionA to B
Linking Race Condition (1)
• Race condition may occur because linking protocol is initiated by both peers
link request link request
link reply link reply
Both attempts succeed
Linking Race Condition (2)
• Check no existing connection or connection attempt, when nodes receive link request
• When nodes receive link error, they restart protocol with random back-off
link request link request
link error link error
link request
link reply
Active linking on?
Random back-off
Joining an Existing NetworkLeaf Connection
• A new node N creates a leaf connection to an initial node I by directly using linking protocol
• I acts as forwarding agent for N
New node N
Leaf connection
Initial node I
Correct positionof new node
Joining an Existing NetworkSend CTM request
• N sends a CTM request addressed to itself over P2P network– the CTM request
contains N’s URI
• A CTM request is received by right and left neighbors, since N is still not in the ring
CTM request
Right neighbor R
Left neighbor L
New node N
Initial node I
Joining an Existing NetworkSend CTM reply
• L and R send CTM reply including their URI to I
• I forwards CTM reply to N
CTM reply
Right neighbor R
Left neighbor L
New node N
Initial node ICTM reply
Joining an Existing NetworkLinking Protocol
• Start linking protocol• L and R send link
request message to N over the physical network
Right neighbor R
Left neighbor L
New node N
Initial node ILink request
Link request
Joining an Existing NetworkComplete Joining
• N forms connections with neighbors and is in ring
• Acquires “far” connections
Right neighbor R
Left neighbor L
New node N
Initial node I
Adaptive Shortcut Creation
• High latencies were observed in experiments due to multi-hop overlay routing
• Shortcut creation– Count IPOP packets to other nodes– When number of packets within an interval
exceeds threshold, initiate connection setup– Because overhead incurred during maintenance
connections, drop connections no longer in use
NAT
Host a NAT Host b
NAT Table192.168.0.2:5000 ⇔ 133.11.23.100:6000
IP: 192.168.0.2 IP: 133.11.238.100 IP: 157.82.13.244
Src: 192.168.0.2:5000Dst: 157.82.13.244:80
Src: 133.11.23.100:6000Dst: 157.82.13.244:80
Src: 157.82.13.244:80Dst: 192.168.0.2:5000
Src: 157.82.13.244:80Dst: 133.11.23.100:6000
Private Network Global Network
NAT TraversalUDP Hole Punching
NAT NATHost A Host B
IP: A IP: N IP: M IP: B
NAT TableA:a ⇔ N:n
NAT TableM:m ⇔ B:b
Src: A:aDst: M:m
Src: B:bDst: N:n
Src: M:mDst: A:a
Src: N:nDst: M:m
Src: M:mDst: N:n
Experimental SetupHosts: 2.4GHz Xeon, Linux 2.4.20,
VMware GSX
Host: 1.3GHz P-III Linux 2.4.21VMPlayer
Host: 1.7GHz P4,Win XP SP2, VMPlayer
Hosts: 2.0 GHz Xeon, Linux 2.4.20,VMware GSX
34 compute nodes, 118 P2P router nodes on PlanetLab
Experiment 1Joining and Shortcut Connections
• Node A: IPOP node• Node B: new joining node
– A and B are in different network domains with NAT
– B sends ICMP packets to A at 1sec intervals
• Within period 1 (about 3 seconds), B establish a route to other nodes
• Within period 2 (about 28seconds), B establish a shortcut connections to A
Experiment 2PVM parallel application: FastDNAml (1)
• Parallelization with PVM based master-workers model
• FastDNAml has a high computation-to-communication ratio
• Dynamic task assignment tolerates performance heterogeneities among computing nodes
Master
Workers
Task Pool
Experiment 2PVM parallel application: FastDNAml (2)
• The execution with shortcuts enabled is 24% faster than that with shortcuts disabled
• The parallel speedup is 13.6x– 23x is reported in previous work in homogeneous
cluster
Sequential Execution
Parallel Execution
Node #2 30 Nodes
Shortcuts disabled Shortcuts enabled
Execution time (sec) 22272 2033 1642
Parallel Speed up n/a 11.0 13.6
Summary
• Introduced WOW– Scalable, fault-resilient and low
management infrastructure
• Future works– Research on middleware which is easy to
use for heterogeneous adaptive Grid environment