Enormous utmp since mpsafetty

Gary Jennejohn gary.jennejohn at freenet.de
Wed Aug 27 14:19:42 UTC 2008

On Wed, 27 Aug 2008 12:50:17 +0100 (BST)
Robert Watson <rwatson at FreeBSD.org> wrote:

> On Wed, 27 Aug 2008, Ollivier Robert wrote:
> > According to Gary Jennejohn:
> >> There are many more pseudo-ttys in /etc/ttys now.  AFAIK utmp allocates an 
> >> entry for every one of them at startup.
> >
> > utmp concepts are ancient.  It is indexed by the tty/pty number so can grow 
> > rather large but it should be a sparse one too.  I remember talks about 
> > replacing it with something a bit more modern.  Backward compatibility is 
> > assured through login(3) although it would break programs digging in the 
> > utmp file itself.  SVR4 had utmp/utmpx and setutline/getutline BTW...
> Right -- utmp growing to 256K would be an excellent example of utmp format 
> inefficiency.  On the other hand, utmp growing to 998M is probably an example 
> of a bug rather than an inefficient design.  freefall.FreeBSD.org, a 
> relatively busy shell box, has a utmp of around 5k, so common use doesn't 
> generally exercise that inefficiency...

But freefall is running FreeBSD 7.0-STABLE #34: Sat Apr 12, so it doesn't
have the new tty stuff running, although I don't suppose that completely
explains the gigantic utmp which OT reported.

Gary Jennejohn

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