Transcript SMOG: A Cloud Platform for Seamless Wide Area Migration of Online Games Virajith Jalaparti, Matthew Caesar, Seungjoon Lee, Jeffery Pang, Jacobus Van der Merwe.

SMOG: A Cloud Platform for
Seamless Wide Area Migration of
Online Games
Virajith Jalaparti, Matthew Caesar,
Seungjoon Lee, Jeffery Pang, Jacobus Van der Merwe
The Cloud on the rise…
Advantages of using the cloud
• Cheaper to use
• On-demand
• Easier maintenance
Multi-million dollar industry
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Hosting games on the cloud?
• Cloud is especially suited for
– Games hosted by individuals- e.g. Counter Strike
– Games with a smaller player population
Problem: Games have stringent Q0S
demands
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How do we design a cloud
platform for online games?
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What do online games require?
• Measurement study on Counter Strike: Source
– Top 1000 servers from Game Tracker
• Determine server stats using qstat
– tcpdump trace from a popular CSS server in
Portland[1]
• Provides information about players IPs
[1] http://www.thefengs.com/wuchang/work/cstrike/
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Requirement 1:
Dynamic Allocation of Resources
• Peak loads shift with time of day:
– Peak in PST associated with trough in GMT
– Move the servers in (say) London to San Francisco
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Requirement 2:
Migration of Servers
Distribution of players in trace from Portland CSS Server
Best server position varies
dynamically with time
Move the server as player
population moves
2pm EDT, 7pm CET
Majority players from
Western Europe (CET)
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7pm EDT, 12am CET
Majority players from
US East Cost (EDT)
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Requirement 3:
Seamless Migration
• Session times vary from ~10sec to ~3hrs
– Need seamless migration for un-interrupted gameplay
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Games need dynamic, seamless
migration of servers
Latency, QoS Requirements
Solution: A platform for Seamless
Migration of Online Games (SMOG)
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Outline
•
•
•
•
•
•
Motivation
Requirements for hosting games
How does SMOG work?
SMOG: Implementation
Evaluation: User study
Conclusion
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SMOG: Goals
Dynamic, Seamless wide-area migration
Application agnostic
No application or network modifications
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SMOG Overview
• Enables migration of game servers across the
wide-area with minimal downtime
• Integrates network route control with virtual
machine migration
– Uses VLANs between datacenters to extend LAN
VM migration techniques
– Uses orchestrated BGP announcements to enable
wide-area reachability
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Seamless wide-area migration with
SMOG
DC A
DC B
GS
PS
LAN Switch
Datacenter Router
PS
Swa
Datacenter
Network
Va
Ra
Swb
VPLS Endpoint
Vb
BGP
/29
Provider Edge router
PEa
PEb
Rb
BGP
/31
Wide-area network
- Advertise
a Migrated
more
prefix
(/31)
through
Rb
and
withdraw
the /29 from Ra
-- GS
Initially
migrates
GS isspecific
toreachable
B using
the
through
VLAN
PEa
(Va
Ra
PEa
 PEb
BGP
Vb)
/29 prefix
GS
from
DC
Ausing
to
DC
B
- External
BGP routing
traffic
- GS issues
an ARPshifts
and isthe
then
reachable via Ra  SWa  Va  PEa  PEb
the wide-area network
Vb  across
SWb
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Server placement in SMOG
• Where to place the game server?
– Optimized for Network QoS
• Latency, variability in RTT etc.
• Formulated as Generalized assignment problem
– Efficient approximation solutions[2]
– Used in SMOG to determine best server location
[2] D. Shmoys and E. Tardos. An approximation algorithm for the generalized assignment problem, 1993
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Outline
•
•
•
•
•
•
Motivation
Requirements for hosting games
How does SMOG work?
SMOG: Implementation
Evaluation: User study
Conclusion
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SMOG: Implementation
• Implemented a real prototype of SMOG on
Shadownet
– Operational trial network with carrier-grade
equipment
• Prototype:
– Xen 3.4.3 used as hypervisor for virtual machines
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SMOG: Implementation
• SMOG extends Xen’s migration capabilities
– Migrate server from DC A to DC B
– Data transferred incrementally in phases
T1
VM suspended
at DC A
Wait on DC A
T3
T4
First packet
received by VM
T2
Migration starts
at DC A
T5
All data received
at DC B
VM starts at
DC B
Timeline
~450msec for Modified
default Xen
Downtime ~150msec
Xen
• Modified Xen to remove the wait condition
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Outline
•
•
•
•
•
•
Motivation
Requirements for hosting games
How does SMOG work?
SMOG: Implementation
Evaluation: User study
Conclusion
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Evaluation: User Study
• Goal: Understand effect of SMOG on user
game play experience
– Do users notice migration downtime?
– Does migration effect user performance?
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User Study: Procedure
GS
RTT = 50 or 200 msec
RTT = 50 or 200 msec
Emulated wide-area
network
• Four gameplay scenarios
– Low RTT (L), High RTT (H)
– Migration (M), No migration (NM)
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User Study: Procedure
• Game play:
– Death match on q3dm1 map of Quake-III
– User plays against a bot in 1-min rounds
• 24 users in total
• Metrics:
– User ratings: 1-10 scale based on “perceived lag”
– Kill count: Measures user’s performance
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User Study: Results
(L-NM, LL-M) = (10, 9)
% difference = -10%
• Difference between ratings vary between -15% to 10%
– Centered around zero
Migration in SMOG is not perceived by users
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User Study: Results
• User kills for L-NM and LL-M are statistically same
• Migration from high latency to low latency is helpful
Migration in SMOG doesn’t affect player performance
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Conclusion
• Games require dynamic, seamless migration
of servers
• SMOG enables seamless migration of online
games in the wide-area
• Evaluation results show SMOG is feasible and
beneficial to users
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Thank you!
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Back up slides
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SMOG: Architecture
SMOG Service
Controller
SMOG Node
Controller (SNC)
Physical
Server (PS)
Game
Server (GS)
Datacenter
Network (DN)
SHP
SNC
Wide-Area Network
PS
DN
SMOG Hosting Platform (SHP)
Player
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Migration Benefits
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