Date: Fri, 29 Aug 2008 11:40:29 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-current@freebsd.org, gary.jennejohn@freenet.de Subject: Re: Enormous utmp since mpsafetty Message-ID: <200808291140.30158.jhb@freebsd.org> In-Reply-To: <20080827161940.1b4403ee@peedub.jennejohn.org> References: <20080826124335.GD3305@carrot.paeps.cx> <alpine.BSF.1.10.0808271248200.96701@fledge.watson.org> <20080827161940.1b4403ee@peedub.jennejohn.org>
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On Wednesday 27 August 2008 10:19:40 am Gary Jennejohn wrote: > On Wed, 27 Aug 2008 12:50:17 +0100 (BST) > Robert Watson <rwatson@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. The new pts entries are after all the 256 pty entries in /etc/ttys, so utmp may be larger becuase the pts entries are "later" in the file (higher offsets). However, if the file is sparse, then it doesn't actually hurt anything. -- John Baldwin
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