Flow Networking in Grid Simulations - Grid Computing: Infrastructure, Service, and Applications - page 387

1000

NetPacket
FlowPacket

100

10

1

0 50 100 150 200 250

File size (MB)

300 350 400 450 500

FIGURE 15.5 Comparison of CPU time needed for “dog-bone” simulation run.

500 MB. We can clearly see that as the size of the i les increase, the overhead
of the NetPacket implementation is demonstrated as the CPU time
explodes. The plot is presented on a log-scale on the y -axis to highlight the
huge difference in simulation running time. The FlowPacket implementa-
tion is totally impervious to the size of the i les being transferred, as it has
no effect whatsoever on the amount of state it maintains. When transmit-
ting several 500 MB i les, the FlowPacket implementation takes 0.432 sec-
onds to execute, while the NetPacket implementation takes a staggering
6699 seconds, or approximately 111 minutes.
We can see a linear relationship between the amount of memory con-
sumed and the size of the i les being transmitted by the GridSim simu-
lator when using the NetPacket implementation in Figure 15.6 . When
utilizing the FlowPacket implementation, the size of the i les being trans-
ferred has no effect on the peak memory consumption, as it stores the
same amount of state regardless of whether it is sending a 0.5 MB i le or a
500 MB i le.
In the second scenario we examine a similar dog-bone topology where
users submit Gridlets for processing, instead of sending i les. A Gridlet is
a construct that contains all the information related to a grid job and
its execution management details such as job length expressed in MI
(Millions Instruction), and the size of input and output i les. Individual
users can model their application by creating Gridlets for processing on
grid resources. These basic parameters are utilized to determine the exe-
cution time, the time required to transport input and output i les between
users and remote resources, and returning the processed Gridlets back to
the originating user along with the results. We have two users submitting