vkernel & GSoC, some questions

[Sergey Babkin]

>From: Matthew Dillon 
>To: John Baldwin <jhb at freebsd.org>

>:Except that you still need "real" hardware concurrency to see some races and 
>:that is important for testing.  I'd worry about the overhead of any 
>
>    Hardware and vkernel/qemu environments exercise different code paths
>    and different timing mechanics.  Certain bugs show up on vkernel's
>    more readily then on real hardware, while other bugs show up more 
>    readily on real hardware then on vkernel's.  I don't think one is 

When testing multi-threaded code I sometimes
insert artificial 
delays at different strategic locations. This widens any present 
race windows and makes the related bugs show up every time instead of 
once in a while. Of course, the resulting code works slower during
the tests too :-)

-SB