On 05/03/2012 08:26 PM, Bill Hooper (whooper) wrote: > I have a request to collect data with a 75%/25% random/sequential mix. > I am having a difficult time figuring out how to get fio to do this. > Any suggestions would be appreciated. That's a good question. There's really no easy way to do that. For random IO, you can do a number of sequential blocks for each random offset generated. But that doesn't give you very fine control of the percentages. For sequential IO, you can skip X bytes for every sequential block read/written. That's really the flexibility that fio has now. Outside of that, you could perhaps use the flow option to have two synchronized jobs with the given weights. But that would throttle one of them, so not ideal if you just want a 75/25 random/sequential running at full speed. I don't think your situation is unique, it would be nice to be able to support a mixed workload like that. One thing I've wanted before (but never implemented) is somewhat related - the option to specify the size of the hot part of the data set. For instance, operate on the full device, but consider region X or size X the hot part which we'll read repeatedly. Would be useful for testing caching. Let me think about how we can best do what you want, and I'll get back to you. -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
