Vaughan-Nichols of ZDNet alerted us that Linux 4.0 will provide support for “no-reboot patching.” The gist: When a security patch or other critical OS update comes out, you can apply it .While rebootless patching is convenient for everyone, it’s a game changer for some applications.
We have used Kitsune to retrofit a half-dozen open-source programs to support dynamic updating.
These include Snort, Tor, Redis, Memcached, Icecast, and vsftpd.
They also perform significant source-to-source compilation of the original program, which adds overhead and can inhibit compiler optimizations.
Kitsune is much gentler on the host application, requiring no static analysis, and very little (potentially no) source-to-source rewriting. In our benchmarks, the time from when a program first signals that an update is required, to the time the program transfers control into Kitsune, to the time when the new version of the program has taken over and finished initializing all state, is generally less than 200ms, and less than 500ms in the worst cases.
At face value, this does not seem to differentiate Kitsune from other C updating systems, like Ginseng or the more recent Up Stare.