In bochs, i can invokes around 40 single step commands in my 2012 mac air. People think qemu is much faster than bochs, it is truth but not for single step. I wrote a java program and keep sending single-step command to qemu through socket (GDB protocol, the average speed is 32 commands per seconds. It would be so slow.
I have meet with a trouble, if i create my own debug server, it is too hard because lot of qemu’ codes are twisted with GDB. If i extends the GDB stub in qemu, the speed cannot be raise.
![qemu gdb stub single step speed](http://peter.kingofcoders.com/wp-content/uploads/2013/08/qemu-worst-300x187.png)
![bochs single step speed](http://peter.kingofcoders.com/wp-content/uploads/2013/08/qemu-worst-2-300x187.png)