3 ms·
By default fio will read or write the whole thing. There are options to control how much will be read or written, perhaps bounded by time rather than space. The
by mgerdts 1y ago
By default fio will read or write the whole thing. There are options to control how much will be read or written, perhaps bounded by time rather than space. The default output format of fio displays the results in both SI (10^x) and IEC (2^x) units per second. Other output formats are available that give values in bytes.
NVMe drive vendors always market size in GB (or TB) and data rates in GB/s.
- ozgrakkurt 1y agoAhh, just realised it also interprets block size as KiB instead of KB. I have this config: bs=512KB size=16GB But it interprets KiB and GiB so this was causing my confusion. The IOPS and timing is basically identical. So output seems fine but it always interprets parameters as SI. Edit: Actually after looking into it more. It seems like there is a good chance that fio reports GiB and KiB in output and it also does the calculation based on that but in reality it uses GB/KB so measurements are a bit wrong.
- mgerdts 1y agofio is a mature widely used tool. It is the only tool that I’ve seen used in the disclosures for performance measurement in NVMe drive datasheets. I’ve used it regularly and see a strong correlation between what it reports and what I can see from other sources measuring the same load. I categorize suggestions by new fio users that they found a bug in fio similarly to how I categorize claims by new C programmers that they found a bug in malloc.
- ozgrakkurt 1y agoOk It was because what I think is a KB is really a KiB. I though KB = 1024 bytes and KiB = 1000 bytes but it is the other way around