Pin-Down Cache: A Virtual Memory Management Technique for Zero-Copy Communication

The overhead of copying data through the central processor by a message passing protocol limits data transfer bandwidth. If the network interface directly transfers the user's memory to the network by issuing DMA, such data copies may be eliminated. Since the DMA facility accesses the physical memory address space, user virtual memory must be pinned down to a physical memory location before the message is sent or received. If each message transfer involves pin-down and release kernel primitives, message transfer bandwidth will decrease since those primitives are quite expensive. We propose a zero copy message transfer with a pin-down cache technique which reuses the pinneddown area to decrease the number of calls to pin-down and release primitives. The proposed facility has been implemented in the PM low-level communication library on our RWC PC Cluster II, consisting of 64 Pentium Pro 200 MHz CPUs connected by a Myricom Myrinet network, and running NetBSD. The PM achieves 108.8 ...

• Type: Conference
• Year: 1998
• Where: IPPS
• Authors: Hiroshi Tezuka, Francis O'Carroll, Atsushi Hori, Yutaka Ishikawa
• Keywords: Distributed And Parallel Computing, IPPS 1998, Message Transfer, Pin-down Cache, Transfer Bandwidth