On 10/10/2013 12:08 PM, Brian L. wrote:
Hi there, I was wondering if you guys use NOOP IO scheduler when you are running fio? I use the CFQ IO scheduler but I do put the OS into init 1 and run fio process one at a time so that I can get accurate readings. I was wondering what are people practice and experience in the real world. Thanks, Brian L.
Some flash device drivers specifically (Fusion-io does this) use the noop scheduler to reduce latency and variance that can be introduced when using other schedulers. Using the no-op scheduler is a reasonable thing to do for all drives to make apples to apples, but if a driver specifically overrides it to something else, probably worth sticking with their settings.
init 1 is overkill. In a previous life doing a lot of measuring of flash - I found that simply making sure the machine was "idle" you could get easily get repeatability within 1% for devices doing several hundred thousand IOPS, even those with on-load architectures that were sensitive to CPU usage.
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