TR-97-8.ps.Z
Y. Dong, X. Du, and X. Zhang
``Characterizing and scheduling communication tasks of parallel and
sequential jobs on networks of workstations",
Computer Communications, Vol. 21, No. 5, 1998, pp. 470-484.
Abstract
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This paper examines the effects of communication interactions of parallel
jobs on a non-dedicated NOW. Three representative communication
patterns of parallel jobs are considered. A quantitative model
to characterize the interactions is proposed. Measurement results
on a NOW support the analytical model, and indicate that the network
interface in the TCP/IP protocol forms a communication bottleneck during
interactions because a standard netwrok interface with single
input/output queue is not able to distinguish communication requests
from parallel and local jobs. Therefore, small but important communication
messages of a parallel job, such as a barrier synchronization, could
be easily blocked by a communication request of a local job, which
could degrade the performance of the parallel job significantly.
A double queue scheme in the network interface is proposed. Using
available information from the protocol layer, the scheme is able to
distinguish the two types of communication requests and give a higher
priority to parallel jobs' communication requests. The simulation
results show that the scheme could improve the performance of parallel
jobs without significantly affecting the performance of local jobs.