i386: 0.991
device: 0.952
graphic: 0.942
x86: 0.907
KVM: 0.877
performance: 0.864
virtual: 0.864
VMM: 0.801
vnc: 0.800
PID: 0.764
kernel: 0.751
boot: 0.722
socket: 0.719
ppc: 0.701
debug: 0.657
architecture: 0.652
arm: 0.646
semantic: 0.639
register: 0.622
network: 0.594
risc-v: 0.571
files: 0.560
mistranslation: 0.558
TCG: 0.553
hypervisor: 0.535
permissions: 0.430
peripherals: 0.414
user-level: 0.340
assembly: 0.285

I tried to use qemu-nbd in the shell script, but it seems that qemu-nbd has some delay.
Description of problem:

Steps to reproduce:
1.
```
cat ~/test.sh
#!/bin/bash
qemu-nbd -c /dev/nbd0 $1
mount -t ntfs3 -o uid=1000,gid=1000 /dev/disk/by-label/OS /mnt/OS
```
2.
```
sudo ~/test.sh ~/VM/win7_i386.qcow2
mount: /mnt/OS: special device /dev/disk/by-label/OS does not exist.
       dmesg(1) may have more information after failed mount system call.

```
Additional information:
But when I added a one-second delay between qemu-nbd and mount commands, the problem was solved.

The qemu-img convert command also has a similar problem. It seems that these commands have a certain delay. Is this in line with expectations?