On Sat, May 29, 2010 at 10:42 AM, Antoine Martin <antoine@xxxxxxxxxxxxx> wrote: > Can someone explain the aio options? > All I can find is this: > # qemu-system-x86_64 -h | grep -i aio > [,addr=A][,id=name][,aio=threads|native] > I assume it means the aio=threads emulates the kernel's aio with > separate threads? And is therefore likely to be slower, right? > Is there a reason why aio=native is not the default? Shouldn't > aio=threads be the fallback? aio=threads uses posix-aio-compat.c, a POSIX AIO-like implementation using a thread pool. Each thread services queued I/O requests using blocking syscalls (e.g. preadv()/pwritev()). aio=native uses Linux libaio, the native (non-POSIX) AIO interface. I would expect that aio=native is faster but benchmarks show that this isn't true for all workloads. Stefan -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
