The idea of improving FUSE performance has become a common theme. There sure are quite a few alternatives to traditional FUSE to consider…Įxtension Framework for File Systems in User space, Ashish Bijlani and Umakishore Ramachandran, USENIX Annual Technical Conference, 2019. I have not had an opportunity to play with this new system yet, but it certainly does seem to be intriguing – and the performance graph from the SNIA presentation is rather compelling, given the massive improvement in scalable performance. FUSE vs ZUFS Performance (from NetApp SNIA presentation) This definitely presents an interesting alternative to using traditional FUSE. What is not currently present in the NetApp repository is an implementation of a user mode persistent file system (they have a dummy file system implementation, which appears to be the base from which one could build a real file system). In such systems, there is no benefit to copying the data from persistent memory into DRAM and back indeed, it is a significant performance impediment. There are a few persistent memory file systems, including UCSD’s NOVA file system, though usually they were developed using emulation of persistent memory. Thus, data is read or written directly from the underlying persistent memory, rather than copied from a buffer cache. Persistent memory benefits from a direct access model, in which traditional file data caching is eschewed in favor of direct access. Their concern appears to be eliminating the copy of any data between kernel and user mode, which makes sense given their objective of supporting persistent memory, such as the new Intel Optane DC Persistent Memory that has recently become commercially available.
The NetApp repositories on contain both a file system reflector ( zufs-zuf), which appears to be similar to the FUSE kernel driver, as well as the user mode server ( zufs-zus) which handles dispatching the kernel level requests to the user mode file system implementations. There have been a variety of talks about this project, including the Linux Plumber’s Conference (which was held next door to me – I can see the venue from my window as I write this), as well as the SNIA Persistent Memory Summit in 2018. After one of my earlier posts on FUSE file system performance, someone mentioned this project to me – the Zero copy Userspace File System project ( ZUFS) which appears to be a NetApp sponsored project.
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