On Tue, Mar 1, 2011 at 5:01 AM, ya su <suya94335@xxxxxxxxx> wrote: > kvm start with disk image on nfs server, when nfs server can not be > reached, monitor will be blocked. I change io_thread to SCHED_RR > policy, it will work unfluently waiting for disk read/write timeout. There are some synchronous disk image reads that can put qemu-kvm to sleep until NFS responds or errors. For example, when starting hw/virtio-blk.c calls bdrv_guess_geometry() which may invoke bdrv_read(). Once the VM is running and you're using virtio-blk then disk I/O should be asynchronous. There are some synchronous cases to do with migration, snapshotting, etc where we wait for outstanding aio requests. Again this can block qemu-kvm. So in short, there's no easy way to avoid blocking the VM in all cases today. You should find, however, that normal read/write operation to a running VM does not cause qemu-kvm to sleep. 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
