Date: Thu, 01 Jul 2004 06:32:57 -0500 From: Jon Noack <noackjr@alumni.rice.edu> To: noackjr@alumni.rice.edu Cc: Daniel Lang <dl@leo.org> Subject: Re: LOR (vm object - swap_pager swhash) Message-ID: <40E3F669.80408@alumni.rice.edu> In-Reply-To: <40E3F3DA.1050702@alumni.rice.edu> References: <20040701061818.GA80579@lucky.net> <20040701063105.GA20785@xor.obsecurity.org> <200407011617.03053.doconnor@gsoft.com.au> <Pine.BSF.4.53.0407010706370.28103@e0-0.zab2.int.zabbadoz.net> <20040701083434.GA83951@atrbg11.informatik.tu-muenchen.de> <40E3DE2D.3020204@alumni.rice.edu> <20040701103535.GA84499@atrbg11.informatik.tu-muenchen.de> <40E3EBD2.2020106@alumni.rice.edu> <40E3EF47.5090007@alumni.rice.edu> <40E3F3DA.1050702@alumni.rice.edu>
next in thread | previous in thread | raw e-mail | index | archive | help
This is a multi-part message in MIME format. --------------090406000108090201010404 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit On 07/01/04 06:22, Jon Noack wrote: > On 07/01/04 06:02, Jon Noack wrote: > >> On 07/01/04 05:47, Jon Noack wrote: >> >>> Perhaps the best bet is to add a FAQ. The FAQ would point to >>> Bjoern's site and the LOR-message would point to the FAQ entry. >> >> >> Again, my docproj foo is weak, but see the attached FAQ. > > > You have to uninstall the xhtml-1.1 port to get docproj to work?!? > Whatever... > > In any case, here's what it would look like: > http://www.noacks.org/freebsd/book.html#LOCK-ORDER-REVERSAL Might help to close the paragraph. Also, add a link to the witness man page. I swear this is the last email... Jon --------------090406000108090201010404 Content-Type: text/plain; name="lor-faq.diff" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="lor-faq.diff" Index: book.sgml =================================================================== RCS file: /home/ncvs/doc/en_US.ISO8859-1/books/faq/book.sgml,v retrieving revision 1.626 diff -r1.626 book.sgml 4381a4382,4426 > > <qandaentry> > <question id="lock-order-reversal"> > <para>What is a <errorname>lock order reversal</errorname>?</para> > </question> > > <answer> > <para>&a.rwatson; answered this question very succinctly on > the freebsd-current list in a thread entitled <quote><ulink > url="http://docs.freebsd.org/cgi/getmsg.cgi?fetch=65165+0+/usr/local/www/db/text/2003/freebsd-current/20031221.freebsd-current">lock > order reversals - what do they mean?</ulink></quote></para> > > <blockquote> > <attribution>&a.rwatson; on freebsd-current, December 14, > 2003</attribution> > > <para>These warnings are generated by Witness, a run-time lock > diagnostic system found in FreeBSD 5-CURRENT kernels (but > removed in releases). You can read more about Witness in the > &man.witness.4; man page, which talks about its capabilities. Among > other things, Witness performs run-time lock order verification > using a combination of hard coded lock orders, and run-time > detected lock orders, and generates console warnings when lock > orders are violated. The intent of this is to detect the > potential for deadlocks due to lock order violations; it's worth > observing that Witness is actually slightly conservative, and so > it's possible to get false positives. In the event that Witness > is accurately reporting a lock order problem, it's basically > saying "If you were unlucky, a deadlock would have happened > here". There are a couple of "well known" false positives, > which we need to do a better job of documenting to prevent > spurious reports. The non-well-known ones typically correspond > to bugs in newly added locking, as lock order reversals usually > get fixed pretty quickly because Witness is busy generating > warnings :-).</para> > </blockquote> > > <note> > <para>See <ulink > url="http://sources.zabbadoz.net/freebsd/lor.html">Bjoern > Zeeb's lock order reversal page</ulink> for the status of > known lock order reversals.</para> > </note> > </answer> > </qandaentry> --------------090406000108090201010404--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?40E3F669.80408>