On Sat, May 29, 2010 at 04:42:59PM +0700, Antoine Martin 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?
The kernel AIO support is unfortunately not a very generic API. It only supports O_DIRECT I/O (cache=none for qemu), and if used on a filesystems it might still block if we need to perform block allocations. We could probably make it the default for block devices, but I'm not a big fan of these kind of conditional defaults. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
