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Date:      Fri, 12 Jan 2001 02:22:50 -0500
From:      Tim McMillen <timcm@umich.edu>
To:        "Jeremy C. Reed" <reed@reedmedia.net>, Marc Tardif <intmktg@CAM.ORG>
Cc:        freebsd-questions@FreeBSD.ORG
Subject:   Re: more info on system processes
Message-ID:  <01011202225000.00410@tim.elnsng1.mi.home.com>
In-Reply-To: <Pine.LNX.4.21.0101101316400.22051-100000@pilchuck.reedmedia.net>
References:  <Pine.LNX.4.21.0101101316400.22051-100000@pilchuck.reedmedia.net>

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On Wednesday January 10, 2001 16:30, Jeremy C. Reed wrote:
> On Thu, 21 Sep 2000, Marc Tardif wrote:
>
> Did you ever get a response to this?
>
> > Where can I get more information about the system processes running
> > on my 4.1-STABLE system (swapper, pagedaemon, vmdaemon, bufdaemon,
> > syncer)? I'd be curious to understand what these processes actually
> > do.
>
> I am also looking for this information. I grep'ed through a bunch of
> sys source and the manual pages, but didn't find much.
>
> > I tried looking for manpages, but nothing was available. I then
> > proceeded to look for "pagedaemon" on freebsd.org's search page (in
> > faq and handbook), but nothing was available either. Short of
> > reading the actual source code, where else can I find information
> > on system processes?
>
> I have been directed to the "The Design and Implementation of the
> 4.4BSD Operating System" book several times. But it seems like this
> should be documented somewhere else (online).

I think that that is really all the documentation there is for some of 
those system processes.  The problem is the hard core kernel hackers 
hate writing documentation.  I even saw someone comment on -hackers 
that they would rather write or debug code for 10 hours than write 
documentation for 1 hour.
	I remember someone stating there was no online documentation about 
those system processes.  There certainly is information about the first 
two at least, in The Design and Implementation.  I'm looking at it now, 
and while I could scan in a few pages, that would violate some 
copyrights.   You probably want to get a hold of the book.  Many good 
libraries have it, or www.bookpool.com has the cheapest price I've seen.
	Here are two summaries from the book.
swapper  is responsible for scheduling the transfer of whole processes 
between main memory and secondary storage when system resources are low
pagedaemon  is responsible for writing parts of the address space of a 
process to secondary storage in support of the paging facilities of the 
virtual memory system.
	Syncer has a manpage, see syncer(4)
	The other two don't appear in the index to D&I, so maybe they are new 
to FreeBSD.  They certainly would not be the only thing undocumented in 
the kernel.  Looks like the source code would be your only place to 
look for info now.
	There is supposed to be a new version of D&I coming out sometime in 
2001 for FreeBSD, that would certainly cover all this.  Hope that 
helped,

							Tim
	


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