Download a sequence preserving efficient packet scheduler using

Proceedings of the International Conference , “Computational Systems and
Communication Technology”
8th , MAY 2010 - by Cape Institute of Technology,
Tirunelveli Dt-Tamil Nadu,PIN-627 114,INDIA
ORDERED ROUND ROBIN SCHEME FOR EFFICIENT PACKET SCHEDULER
J.JENIFERJOSE, PG scholar, Department of IT,
Francis Xavier Engineering College, Tirunelveli.
E-mail:[email protected]
J.Monica Esther , Lect/IT - Francis Xavier Engineering College, Tirunelveli.
ABSTRACT
Network processors (NPs) has many
computation-intensive tasks such as routing table
lookup, classification, IPSec, and multimedia
transcoding can be accomplished more easily in a
router. An NP consists of a number of on-chip
processors to carry out packet level parallel
processing operations. Ensuring good load
balancing among theprocessors increases
throughput. However, such multiprocessing also
gives rise to increased out-of-order departure of
processed packets. In this paper, we propose an
Ordered Round-Robin (ORR) scheme to schedule
packets in a heterogeneous NP assuming that the
workload is perfectly divisible. The processed
loads from the processors are ordered perfectly.
We analyze the throughput and derive expressions
for the batch size, scheduling time, and maximum
number of schedulable processors. To effectively
schedule variable length packets in an NP, we
propose a Packetized ORR (P-ORR) scheme by
applying a combination of deficit round-robin
(DRR) and surplus round-robin (SRR) schemes.
Index Tterms- Load balancing, in-order delivery,
Scheduler, Ordered round robin
I. INTRODUCTION
Round-robin is one of the simplest
scheduling algorithms for processes in an
operating system, which assigns time slices to
each process in equal portions and in circular
order, handling all processes without priority.
Round-robin scheduling is both simple and easy to
implement, and starvation-free. Round-robin
scheduling can also be applied to other scheduling
problems, such as data packet scheduling in
computer networks. Round-robin job scheduling
may not be desirable if the size of the jobs or tasks
are strongly varying. A process that produces large
jobs would be favored over other processes. This
problem may be solved by time-sharing, i.e. by
giving each job a time slot or quantum
allowance of and interrupt the job if it is not
completed by then. The job is resumed next time
a time slot is assigned to that process. A
multiplexer, switch or router that provides
round-robin scheduling has a separate queue for
every data flow, where a data flow may be
identified by its source and destination address.
The algorithm lets every active data flow to take
turns in transferring packets on a shared channel
in a periodically repeated order. The scheduling
is non-work conserving, meaning that if one
flow is out of packets, next data flow will take
its place.
These services demand service differentiated
and application oriented processing at network
nodes with quality of service provision .Given
the processing power limitation of single
processor and the inherent parallelism associated
with network traffic, parallel processing is
becoming increasingly attractive. Applicationoriented services often carry stringent
performance
requirements,
which
are
increasingly handled by multicore processors.
As such, several companies have Introduced
powerful network processors (NPs) that can be
placed in routers to execute various tasks in the
network. These tasks can range from IP level
table lookup algorithm to application level
multimedia transcoding applications. Such an
NP-based
router
permits
sophisticated
computations within the network by allowing
their users to inject customized programs into
the nodes of the network.
Proceedings of the International Conference , “Computational Systems and Communication
Technology”
8th , MAY 2010 - by Cape Institute of Technology,
Tirunelveli Dt-Tamil Nadu,PIN-627 114,INDIA
Fig.1. Packet scheduling model for network
processor
Objective
The aim of this project is to derive an efficient
packet scheduling algorithm in an NP that
comprises a number of processors for packet
processing. It should provide
 Load balancing for processing
variable length Packets using a group
of heterogeneous Processors .
 In-order delivery of packets without
considering receiver’s rearranging
capability.
II. RELATED WORKS
In [6] we propose a new version of
TCP that maintains high throughput when
reordering occurs and yet, when packet reordering
does not occur, is friendly to other versions of
TCP. The proposed TCP variant, or TCP-PR, does
not rely on duplicate acknowledgments to detect a
packet loss. Instead, timers are maintained to keep
track of how long ago a packet was transmitted. In
case the corresponding acknowledgment has not
yet arrived and the elapsed time since the packet
was sent is larger than a given threshold, the
packet is assumed lost. Because TCP-PR does not
rely on duplicate acknowledgments, packet
reordering has no effect on TCP-PR's performance
In Existing system First-Come-First- Serve
(FCFS) basis and combines the traffic back into
a single stream onto the output port. The aim of
the packet scheduling algorithm is twofold. The
input load is balanced among the processors P1
through Pm. The flow order is maintained when
the packets are transmitted to the transmitting
processor pt.
In NPs, the packets are processed on the
worker processors Finally, the transmitting
processor in an NP removes the packets from the
worker processors on an FCFS basis, whereas
the receiving processor in the striping model
executes a resequencing algorithm. In[4]we first
propose an Ordered Round Robin (ORR)
scheme to schedule packets in a heterogeneous
network processor assuming that the workload is
perfectly divisible. The processed loads from the
processors are ordered perfectly. We analyze the
throughput and derive expressions for the batch
size, scheduling time and maximum number of
schedulable processors. To effectively schedule
variable length packets in an NP, we propose a
Packetized Ordered Round Robin (P-ORR)
scheme by applying a combination of deficit
round robin (DRR) and surplus round robin
(SRR) schemes. We extend the algorithm to
handle multiple flows based on a fair scheduling
of flows depending on their reservations.
Extensive sensitivity results are provided
through analysis and simulation to show that the
proposed algorithms satisfy both the load
balancing and in-order requirements for parallel
packet processing.
III. WORKING OF EFFICIENT PACKET
SCHEDULER USING ORDERED ROUND
ROBIN SCHEME
:
An
efficient
packet
scheduling
algorithm, P-ORR, that is capable of scheduling
variable length packets among a group of
heterogeneous processors to ensure both load
balancing and minimal out of- order packet
delivery. P-ORR is based on the ORR algorithm,
which we developed from rigorous theoretical
derivation by assuming that the workload is
perfectly divisible.
Proceedings of the International Conference , “Computational Systems and Communication
Technology”
8th , MAY 2010 - by Cape Institute of Technology,
Tirunelveli Dt-Tamil Nadu,PIN-627 114,INDIA
Fracti
on1
Packet1
Packet
2
Packe
tn
Dispa
tcher
Fracti
on2
Fractio
nm
processed loads from the processors are ordered
perfectly.
Work
processor1
Work
Processor2
Transmit
ter
Process
or
Term
inal
Work
Processor m
Fig :2 System model
In the proposed system packets are
processed in an NP, there are three steps:
1. D-step: the dispatching processor dispatches the
packet worker processor
2. P-step: the worker processor processes the
packet
Fig.5.1. Congestion Detection
3. T-step: the worker processor sends the packet to
the transmitting processor.
This figure shows how to detect the
congestion in variable length packets.
IV. FUTURE WORKS
Fair Scheduling Among Multiple Flows
A P-ORR algorithm is used to schedule
incoming packets among multiple processors with
basic assumption that all the incoming packets are
a treated equally. However packets may belong to
different network flows that have made different
reservations. In order to handle such packets PORR algorithm is extended to provide fair
scheduling among multiple flows. Congestion
control concerns controlling traffic entry into a
telecommunications network, so as to avoid
congestive collapse by attempting to avoid
oversubscription of any of the processing or link
capabilities of the intermediate nodes and
networks and taking resource reducing steps, such
as reducing the rate of sending packets. It should
not be confused with flow control, which prevents
the sender from overwhelming the receiver.
A Packetized ORR (P-ORR) scheme by
applying a combination of deficit round-robin
and surplus round-robin schemes.
V. EXPERIMENTAL RESULTS
V. CONCLUSION
Ordered Round-Robin (ORR) scheme to
schedule packets in a heterogeneous NP assuming
that the workload is perfectly divisible. The
In this phase, an efficient packet
scheduling algorithm PORR is implemented,
which is capable of scheduling variable length
Fig.5.2. Packetized Ordered Round Robin
Proceedings of the International Conference , “Computational Systems and Communication
Technology”
8th , MAY 2010 - by Cape Institute of Technology,
Tirunelveli Dt-Tamil Nadu,PIN-627 114,INDIA
packets among a group of heterogeneous
processors to ensure both load balancing and
minimal out of-order packet delivery.
P-ORR is based on the ORR algorithm,
which assumes that the workload is perfectly
divisible. The PORR algorithm satisfies both the
load balancing and in-order requirements for
packet transmission. In order to minimize the
performance discrepancy between ORR and PORR, a new packetized technique to better address
the problem of variable packet length is also used
in this project This work can be extended to design
an optimal mapping between multiple flows and
processors and the derivation of fairness bounds.
VI. REFERENCES
1. M.Shreedhar and G. Varghese, “Efficient Fair
Queuing Using Deficit Round Robin,” IEEE/ACM
Trans. Networking, vol. 4,pp. 375-385, June 1996.
2. Y.C. Cheng and T.G. Robertazzi, “Distributed
Computation with Communication Delays,” IEEE
Trans. Aerospace and Electronic Systems, vol. 24,
no. 6, pp. 700-712, Nov. 1988.
3. L. Kencl and J.Y.L. Boudec, “Adaptive Load
Sharing for Network Processors,” Proc. IEEE
INFOCOM, 2002.
4. J.A. Cobb and M. Lin, “A Theory of MultiChannel Schedulers for Quality of Service,” J.
High Speed Networks, vol. 12, nos. 1,2, pp. 61-86,
2002.
5. J. Guo, F. Chen, L. Bhuyan, and R. Kumar,
“A Cluster-Based Active Router Architecture
Supporting Video/Audio StreamTranscoding
Services,” Proc. 17th Int’l Parallel and
Distributed Processing Symp. (IPDPS ’03), Apr.
2003.
6. T.G. Robertazzi, “Ten Reasons to Use
Divisible Load Theory,” Computer, vol. 36, no.
5, pp. 63-68, May 2003.
7. B. Wu, Y. Xu, H. Lu, and B. Liu, “An Efficient
Scheduling Mechanism with Flow-Based Packet
Reordering in a High-Speed Network
Processor,” Proc. IEEE Workshop High
Performance Switching and Routing (HPSR),
2005
8. J. Guo, J. Yao, and L. Bhuyan, “An Efficient
Packet Scheduling Algorithm in Network
Processors,” Proc. IEEE INFOCOM ’05,vol. 2,
pp. 807-818, Mar. 2005.
9. S. Bohacek, J.P. Hespanha, and J. Lee, “A
New TCP for Persistent Packet Reordering,”
IEEE/ACM Trans. Networking, vol. 14, no. 2,pp.
369-382, Apr. 2006.
10. Shi and L. Kencl, “Sequence-Preserving
Adaptive Load Balancers,” Proc. ACM/IEEE
Symp. Architectures for Networking and Comm.
Systems (ANCS ’06), pp. 143-152, Dec. 2006.