Jail to jail network performance?

[Brandon Fosdick]

Robert Watson wrote:
> There are several ways you can do it, but they generally fall into two
> classes of activies:
> 
> (1) Modifying the name space exclusion assumption for jails, so that the
>     file system name spaces overlap.  One way to do this is with nullfs.
> 
> (2) Having a daemon or tool that runs outside of the jail and brokers
>     communication between the jails.  One example might be a daemon that
>     inserts a UNIX domain socket into both jails and then provides
>     references to shared IPC objects between the two "by request".
>     Another example might be a daemon or tool that responds to a request
>     and creates a hard link from a socket/fifo endpoint visible in one
>     jail to a name visible in another jail, perhaps when setting up the
>     jail.  The former requires more infrastructure, but the latter is less
>     flexible.

The jail(8) man page says that if the MIB security.jail.sysvipc_allowed=1 processes inside a jail can use IPC to talk to stuff in other jails. How does that affect mysql in a jail? Do I need this enabled to run mysql?