FUSE Gets I/O Performance Improvements
Written by Michael Larabel in Linux Kernel on 15 December 2012 at 11:29 AM EST. 8 Comments
The FUSE module, which allows for file-systems to be run from user-space, can now process direct I/O a-synchronously. This a-synchronous direct I/O can lead to very noticeable performance improvements for FUSE-based file-systems like ZFS.

One of the most common complaints about the FUSE project for running file-systems in user-space has been the poor performance. While using FUSE leads to portability between operating systems, simplified file-system implementations, pushing file-systems that would not be allowed in the GPL-licensed Linux kernel, and a stable API, the performance has always been a problem compared to file-systems natively implemented within the Linux kernel.

There have been FUSE performance improvements over the years, but it's still an active complaint. Linus Torvalds called FUSE a toy and for misguided people. The latest I/O performance improvement for FUSE is being able to process direct I/O a-synchronously.

Maxim Patlasov submitted a set of six patches for allowing the direct I/O to be done a-synchronously rather than synchronously as it's done currently.
Existing fuse implementation always processes direct IO synchronously: it submits next request to userspace fuse only when previous is completed. This is suboptimal because: 1) libaio DIO works in blocking way; 2) userspace fuse can't achieve parallelism processing several requests simultaneously (e.g. in case of distributed network storage); 3) userspace fuse can't merge requests before passing it to actual storage.

The idea of the patch-set is to submit fuse requests in non-blocking way (where it's possible) and either return -EIOCBQUEUED or wait for their completion synchronously. The patch-set to be applied on top of for-next of Miklos' git repo.
Performance tests done by the patch-set's author show the dd read speeds on FUSE going up by 19%, dd writes going up by about 4%, AIO-Stress reads going up by 21%, and AIO-Stress writes increasing by 11%.
About The Author
Author picture

Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter or contacted via MichaelLarabel.com.

Related Linux Kernel News
Popular News
Trending Reviews & Featured Articles