I/O benchmarks with Fio

Disk Tuner

Article from ADMIN 05/2011

By Martin Steigerwald

Fio can help you measure performance by simulating different loads and measuring bandwidth, I/O operations per second, latency, and CPU load.

The maintainer of the Linux kernel block device layer, Jens Axboe, developed the Fio tool to measure performance in various applications. Simple benchmarks, such as hdparm or dd, have limits to their capabilities. They might test only sequential I/O, for example, which isn't particularly significant for normal workloads with many small files. On the other hand, writing a separate test program for each workload is pretty time-consuming.

The current version of Fio is 1.57. I have created a package for Debian that the Ubuntu developers integrated into Ubuntu. If you have SUSE versions since SLES 9 and openSUSE 11.3, the benchmark repository offers an up-to-date package [1]. Fio is also included with Fedora. The source code from the tarball or Git repository can be compiled with a simple make, assuming you have the libaio developer files in place. For Debian and its derivatives, this file would be libaio-dev; for RPM-based distributions, it's typically libaio-devel [2][3]. Fio also will run quite happily on BSD variants and Windows, as the documentation explains. An I/O workload comprises one or multiple jobs. Fio expects the job definitions as parameters at the command line or as job files in the ini format used by Windows and KDE.

The following simple call to Fio

fio --name=randomread --rw=randread --size=256m

sets up a job titled randomread and then executes the job. To allow this to happen, Fio creates a 256MB file in the current directory along with process for the job. This process reads complete file content in random order. Fio records the areas that have already been read and reads each area once only. While this is happening, the program measures the CPU load, the bandwidth

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