Martin von Loewis <martin@mira.isdn.cs.tu-berlin.de> writes:
> > > How important is it to have the update daemon running? What would be the
> > > consequence(s) if it is not loaded? In other words, is it really necessary?
> >
> > It's an offtopic here. No, it's not really important to run update. The
> > only thing it does - sync() every 30 second.
>
> I don't think it's off-topic, and I think this answer is wrong.
> On most Linux installations, update is the same as bdflush. bdflush used
> to invoke the kernel flush mechanism, essentially providing a thread.
In 2.0+ kernels, kflushd is actually a kernel thread spawned
automatically during boot. bdflush/update does nothing other than do
a sync() every so often.
> Now that there is the kflushd, the question is valid whether a user
> process still needs to initiate flushing.
Yes. The kflushd thread is triggered by internal kernel events when
the kernel needs to flush things to balance its memory usage. If the
kernel is not short of memory at all then kflushd won't be busy, so
you still need the regular sync() of the user process.
Cheers,
Stephen.