As some Phoronix Premium members have requested CPU usage results during file-system tests, there are some included in this article.
As shown above, the CPU utilization for the Intel Core i7 was actually higher than that when ZFS-FUSE on Linux was being used or when OpenSolaris was being run with its native ZFS implementation.
While the CPU load was lower when using ZFS-FUSE during the PostMark benchmark, the difference was only a few percent. When running Apache, the CPU usage spiked dramatically and was much higher than that of the native Linux file-systems that were tested to the point that it was almost three times greater.
There is certainly a performance penalty incurred when using ZFS-FUSE on Linux, which may or may not be justified depending upon whether you take advantage of any other features found in the Oracle/Sun ZFS file-system. Even with the very latest Linux 2.6.36 kernel and both the latest stable and unstable releases of the ZFS-FUSE code-base, a significant drop in performance can be measured when running ZFS in user-space. It will be interesting though to see how the native ZFS Linux module from either the Lawrence Livermore National Laboratory or KQ Infotech performs compared to ZFS-FUSE. Even the native ZFS module on OpenSolaris was no match to Linux and EXT4/Btrfs, so our next set of native ZFS Linux results should be rather interesting. It could be argued that those OpenSolaris-compatible test profiles just so happened to be bottlenecked elsewhere in the Solaris Nevada kernel, but even ZFS on FreeBSD is slow when compared to the EXT4 and Btrfs file-systems. These next ZFS on Linux results will be available in September if the native ZFS beta code arrives prior to the annual Oktoberfest outing -- stay tuned for this year's Phoronix gathering details.
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