Interval-based registration cache for zero-copy protocols - 2007

Interval-based registration cache for zero-copy protocols - 2007

Abstract - Zero-copy protocols are essential for large message performance in high-speed networking. But these require costly memory registration mechanisms to allow the network interface to access user-space memory. MYRINET EXPRESS nowadays offers a basic registration cache scheme to reduce the overhead of that memory registration, but maintaining its consistency yet forces the user-space to monitor any changes in the virtual memory, which we show to be inefficient. After integrating ”VMA spy 2” in the LINUX kernel to perform this monitoring inside the kernel in a reliable way, we modify MYRINET EXPRESS to use it. We then demonstrate that MYRINET EXPRESS current implementation of the registra- tion cache suffers from weaknesses. We therefore add a new caching facility in the MYRINET EXPRESS driver, giving it a reasonable grain-size that we show to be more adapted that DMA windows. MYRINET EXPRESS is then modified to integrate that new cache. We eventually demonstrate how our two possi- bly independent contributions are helping to improve registration cache techniques and consequently zero-copy protocols.

Keywords: zero-copy, memory pinning, cache registration, LINUX kernel, MYRINET EXPRESS, high-speed networking, operating systems.
 
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