Replacing rc(8) (Was: FreeBSD Boot Times)

[RW]

On Tue, 19 Jun 2012 01:04:47 -0400
Richard Yao wrote:

> On 06/19/2012 12:39 AM, Wojciech Puchar wrote:
> > - delay at rc.d scripts - there are some delays inserted.
> > 
> >> The latter item is the only place where making changes to rc.d is
> >> going to help, and only then by parellelizing, and even then you
> >> are not really going to gain much since most things at boot time
> >> are serial.
> > 
> > grep sleep /etc/rc.d/* usr/local/etc/rc.d/*
> > 
> >>
> >> So while talk of how to get your favorite boot-time manager into
> >> FreeBSD may be entertaining, it's not likely to be productive, and
> >> almost
> > 
> > it is unimportant as FreeBSD don't crash.
> 
> OpenRC init scripts lack such delays. They store dependency
> information, which enables OpenRC to start them as soon as their
> dependencies are ready.

That's not the reason for the sleeps. FreeBSD sorts the scripts into
dependency order and runs them sequentially, so there's no reason
to sleep waiting for a dependency script to complete. The sleeps
exist for a variety of reasons. 

Just looking at the grep can be a bit misleading. Not all of the
scripts are going to be used, the sleep is not always relevant to
startup, in some case it's in a code path that's not typically taken.

One thing that I think could be easily improved is that the polling
delays could be changed from  1 second to 0.1 seconds. If there's a
reason for rc scipts needing to be portable, there could be a polling
delay function with a "fast polling" option in defaults/rc.conf.