1. Industrial Issues in Software Performance
Aman Shaikh
AT&T Labs - Research
June 24, 2008
7th International Workshop on Software and Performance
Princeton
Acknowledgement: Alan Glasser, Kobus van der Merwe, Jennifer Yates

2. Communication service providers
Introduction
Communication service providers
Various services: voice, video, data
Various ways of connecting to customer
Ethernet, Frame Relay, ATM, Wireless, …
Trend towards supporting all communication over IP-based core network
Today’s IP networks and services
Thousands of equipments and systems have to work in tandem
Routers, switches, servers, line cards …
Provisioning, configuration, trouble-shooting, maintenance, capacity planning, billing, …
Huge amalgamation of hardware and software
Industrial Issues in Software Performance

3. Challenges of Managing Networks
Lack of management support
Absence of standardization in network management
Solutions often develop in an organic fashion
Scale
Hundreds of offices, thousands of routers, hundred thousands of line cards and transport facilities
Heterogeneity
Different kinds of equipments
Example: routers, switches, servers, line cards, …
Different vendors and models for same equipment
Example of router vendors: Cisco, Juniper, Alcatel, …
Cisco router models: CRS, GSR, 7200 series, …
Variety of service offerings with wide variety of features
Industrial Issues in Software Performance

4. Challenges of Managing Networks
Constant churn
Customers, services, technology
Explosive growth
Internet traffic is predicted to double every two years
More stringent requirements and expectations
Service delivery model of IP is best effort
Works for original applications of the Internet: file transfer, and newsgroup
Applications such as VoIP, IPTV, gaming require strong performance guarantees from the network
Deliver packets reliably within a certain time bound
Security
Internet’s intrinsic model: “Trust every packet and do not charge for it”
Industrial Issues in Software Performance

5. Tier-1 Service Provider Network
DWDM
systems C P C P
OC-48 or OC-192 DWDM
PoP C P C P C P
Intercity E PE C P
PoP E PE C P C P E PE C P C P E PE E PE
Customer facing PE interfaces
PoP
Metro
Rough Numbers
100s of offices
100s of Ps, 1000s of PEs, 10000s of CEs
100,000s of transport facilities
LEC CE
CPE
Access CE
CPE
PoP: Point-of-Presence
P: Backbone (core) Router
PE: Provider Edge Router
CE: Customer Edge Router
Industrial Issues in Software Performance

6. The Software above it!
Taken from SIGCOMM 2005 Tutorial by Aman Shaikh & Albert Greenberg
Database 1
Databases
Database 2
Database 3
abc
def
ghi
Ticket Management
Mgt 1
xxx
Mgt 3
Mgt 4
Mgt 2
xyz
nms
ISE
Mgt sys xyz
CFKB
Transport 1 2 3 5 6 7 9 11 13 14 19 20
DB3
DB4
DB2
DB1
ABC
Platform for task xyz
Portal abc
NF-TA
CAPRI
Platform xyz 21
Portals
abct
xxx!
xxxx
yyy
zzzzz
Platform for doing xyz
abce 23 24 25 18
gef 26
System for xyz 27
Platform for abc
Platform for xyz
System X
platform for xyz
dsagjag
Dga;ljag;lkj
yyz
xyzr
abc1
abc5
abc2
abc3
abc4
mno
To another sys
occ 28 29
Task xyzs 30
To abc
Industrial Issues in Software Performance

7. Implications for Software Requirement
Need to translate network requirements into software requirements
Example: what does five-9’s of availability mean for software on a router?
Need to determine performance requirement for tomorrow, not today
Accommodate for growth that occurs during expected life-time of a software
Industrial Issues in Software Performance

8. Implications for Software Development
How to write reliable and robust software?
Systems need to work 24 x 7
Under non-deterministic and unpredictable environment
Systems should handle errors and overload gracefully
Systems should support hit-less upgrade
How to write scalable and extensible software?
Software often lives longer than originally anticipated
How to integrate software with existing systems?
Integration with legacy software often a challenge
Implication for performance
Cater to lowest common denominator
Exploit opportunities available for parallelism
Industrial Issues in Software Performance

9. Implications for Software Testing
How to generate network-like conditions during testing?
Enumerating all possible conditions is infeasible
However, “untested feature interaction” can lead to problems
Creating network scale is nearly impossible
Simulators and emulators do exist, but do not always scale to the extent of large real networks
Industrial Issues in Software Performance

10. My World-View Knowing performance requirements upfront is vital
But in real world, this is often not possible
Or performance requirements change/evolve over time
Due to growth
Longer than expected shelf-life of software
How to cope with evolving performance requirements?
Analyze how software is likely to scale with input parameters
Those Big-Oh and Big-Omega’s are important
Use tools to determine actual performance
Humans not very good judge of performance and bottlenecks
Have a modular design
Cleanly separate interface and implementation
(Re)-use existing libraries/modules
Document, document, document, …
So that someone else can pick up the threads
Or you yourself don’t feel lost when you re-visit your code
Industrial Issues in Software Performance