On Fri, 04/10 22:38, ein wrote: > Qemu creates more than 70 threads and everyone of them tries to write to > disk, which results in: > 1. High I/O time. > 2. Large latency. > 2. Poor sequential read/write speeds. > > When I limited number of cores, I guess I limited number of threads as > well. That's why I got better numbers. > > I've tried to combine AIO native and thread setting with deadline > scheduler. Native AIO was much more worse. > > The final question, is there any way to prevent Qemu for making so large > number of processes when VM does only one sequential R/W operation?
aio=native will make QEMU only submit IO from the IO thread, so you shouldn't see 70 threads with that. And that should usually be a better option for performance. Fam
