Date: Tue, 13 Jan 2015 17:30:54 -0500 From: Garrett Wollman <wollman@bimajority.org> To: freebsd-fs@freebsd.org, freebsd-stable@freebsd.org Subject: Some filesystem performance numbers Message-ID: <21685.40094.453028.585630@hergotha.csail.mit.edu>
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I recently bought a copy of the SPECsfs2014 benchmark, and I've been using it to test out our NFS server platform. One scenario of interest to me is identifying where the limits are in terms of the local CAM/storage/filesystem implementation versus bottlenecks unique to the NFS server, and to that end I've been running the benchmark suite directly on the server's local disk. (This is of course also the way you'd benchmark for shared-nothing container-based virtualization.) I have found a few interesting results on my test platform: 1) I can quantify the cost of using SHA256 vs. fletcher4 as the ZFS checksum algorithm. On the VDA workload (essentially a simulated video streaming/recording application), my server can do about half as many "streams" with SHA256 as it can with fletcher4. 2) Both L2ARC and separate ZIL have small but measurable performance impacts. I haven't examined the differences closely. 3) LZ4 compression also makes a small performance impact, but as advertised, less than LZJB for mostly-incompressible data. I hope to be able to present the actual benchmark results at some point, as well as some results for the other three workloads. -GAWollman
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