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Is there a performance impact from using a user space file system vs a kernel space filesystem? I ask because I have a friend that refuses to use user space file systems because of a performance impact. I've done some research but cannot find any benchmarks of user-space vs kernel-space file systems.

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He's arguing that user-space filesystems are faster? – Shane Madden Sep 5 '12 at 2:06
If he doesn't use kernel-space file systems, how on earth does he boot his computer? – Michael Hampton Sep 5 '12 at 2:14
Typo, he doesn't use user space file systems because of "performance" impacts. – jersten Sep 5 '12 at 2:30
We kind of figured as much. Sure, the performance is usually slightly worse with a userspace filesystem, as @sysadmin1138 noted in his answer. But performance is not the sole criterion for choosing a filesystem, and so sometimes using one is the right thing to do. – Michael Hampton Sep 5 '12 at 3:54
up vote 2 down vote accepted

There is a research paper out there titled, Performance and Extension of User Space File Systems by Aditya Rajgarhia (Stanford) and Ashih Gehani (SRI) that goes into exactly what you're looking for. It is easily locatable.

The conclusions reached match my own perceptions of this that user-space file-systems (FUSE specifically) do perform measurably worse than kernel-space filesystems. They go into much more detail about their findings.

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