On Wed, 17 Oct 2018 at 22:45, Elliott, Robert (Persistent Memory) <elliott@xxxxxxx> wrote: > > > These will make each thread implement your desired mix: > > rwmixread=int [...] > rwmixwrite=int [...] > percentage_random=int[,int][,int] [...] Another (but more overlooked) option for forcing different jobs into lockstep with each other is the flow parameter - https://fio.readthedocs.io/en/latest/fio_doc.html#cmdoption-arg-flow but it tends to be easiest to reason about when there are just two jobs. > > Threads running sequential accesses can easily benefit from cache hits from each other, if > there is any caching or prefetching done by the involved drivers or devices. One thread > takes the lead and suffers delays, while the others benefit from its work and stay close > behind. They can take turns, but tend to stay clustered together. This can distort results. > Random accesses avoid that problem, provided the capacity is much larger than any caches. -- Sitsofe | http://sucs.org/~sits/
