Il 23/01/2013 09:58, Dietmar Maurer ha scritto: >>>>> Are you using timers in any way? >>>> >>>> Yes, I call co_sleep_ns(rt_clock, delay) to limit rate to output >>>> stream. >>> >>> Use block_job_sleep_ns instead, and only call it when no I/O is pending. >> >> Thanks, that works! > > I currently use qemu_aio_set_fd_handler() to implement async output to > the backup stream. While that works, performance is much better (during > backup) > if I use a separate thread to write the data. > > Is that known behavior, or should aio give about the same performance as > using a thread?
It depends, but this is what we saw for migration too. You may also have less contention on the big QEMU lock if you use a thread. > Or would I get better performance if I use Linux native AIO support? That also depends, but in general it should be faster. Paolo
