Implementation ofa Reliable Remote Memory Pager
Evangelos P. Markatos and George Dramitinos
Computer Architecture and VLSI Systems Group
Institute of Computer Science (ICS)
Foundation for Research & Technology - Hellas (FORTH), Crete
Abstract
Traditional operating systems use magnetic disks as paging devices,
even though the cost of a disk transfer measured in processor cycles
continues to increase. In this paper we explore the use of remote
main memory for paging. We describe the design, implementation and
evaluation of a pager that uses main memory of remote workstations as
a faster-than-disk paging device and provides reliability in case of
single workstation failures. Our pager has been implemented as a
block device driver linked to the DEC OSF/1 operating system, without
any modifications to the kernel code. Using several test applications
we measure the performance of remote memory paging over an Ethernet
interconnection network and find it to be faster than traditional disk
paging. We evaluate the performance of various reliability policies
and prove their feasibility even over low bandwidth networks, like
Ethernet.
We conclude that the benefits of reliable remote memory paging in
workstation clusters are significant today and will probably increase
in the near future.
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