Date: Fri, 16 Jan 2009 13:51:29 +0000 (GMT) From: Robert Watson <rwatson@FreeBSD.org> To: Pete French <petefrench@ticketswitch.com> Cc: freebsd-stable@freebsd.org, drosih@rpi.edu, dchagin@freebsd.org, rblayzor.bulk@inoc.net Subject: Re: Big problems with 7.1 locking up :-( Message-ID: <alpine.BSF.2.00.0901161347030.21561@fledge.watson.org> In-Reply-To: <E1LNopy-0004ZF-AW@dilbert.ticketswitch.com> References: <E1LNopy-0004ZF-AW@dilbert.ticketswitch.com>
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On Fri, 16 Jan 2009, Pete French wrote: >> hi, please type: show lock 0xffffff0001254d20 and then show thread >> 0xXXXXXXXXXXX where XXXXX is 'owner' of previous output. > > http://toybox.twisted.org.uk/~pete/71_pdns_lock.png > > That's in Power DNS - which is interesting because the one difference > between the boxes that lock and those which dont is that the locking ones > are serving DNS. I rather feared as much. Let's run down the path of "perhaps there's a problem with the new UDP locking code" for a bit and see where it takes us. Is it possible to run those boxes with WITNESS -- I believe that the fact that "show alllocks" is failing is because WITNESS isn't present. The other thing we can do is revert UDP to using purely write locks -- the risk there is that it might change the timing but not actually resolve the bug, so if we can analyze it a bit using WITNESS first that would be useful. Robert N M Watson Computer Laboratory University of Cambridge
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