Date: Fri, 20 Aug 2004 22:29:50 +0400 From: Roman Kurakin <rik@cronyx.ru> To: John Baldwin <jhb@FreeBSD.org> Cc: Robert Watson <rwatson@FreeBSD.org> Subject: Re: Tracking down LORs Message-ID: <4126431E.9010702@cronyx.ru> In-Reply-To: <200408201302.26421.jhb@FreeBSD.org> References: <Pine.NEB.3.96L.1040820001041.20697B-100000@fledge.watson.org> <4125B172.9060303@cronyx.ru> <200408201302.26421.jhb@FreeBSD.org>
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John Baldwin wrote: >On Friday 20 August 2004 04:08 am, Roman Kurakin wrote: > > >>Robert Watson wrote: >> >> >>>On Fri, 20 Aug 2004, Roman Kurakin wrote: >>> >>> >>>> Currently I am trying to track down a couple of LORS in my code. >>>>But it seems that I do not undestand smth or all things id realy so bad. >>>> >>>> >>>I find it's very helpful to add lock orders to the hard-coded lock order >>>table in subr_witness.c. Without hard-coded entries, WITNESS will >>>dynamically build an order based on observed lock use. This is generally >>>fine, but once in a while the "wrong" order will be used before the >>>"right" order, so the lock order warning will print for the "right" order, >>>leaving less useful debugging information. The table allows the >>>definition of partial orders, so you can specify relationships between >>>subsets of mutexes of interest. WITNESS will flesh out remaining orders >>>through dynamic discovery. >>> >>> >>I'll try to go this way, since I am in dead end. >> >> > >Note that some lock orders as also inferred via transitivity. > >For example, let's say you have three locks a, b, and c. One thread locks a >then b, so witness saves that order. A second thread locks b then c, so >witness saves that order. If a third thread tries to lock c then a, an LOR >will result. This is similar to how > is transitive, i.e. if a > b and b > >c, then a > c. > > It looks like I have smth like that. But I am get stuck with boot loader problem for now :-( I switched to that problem since that machine was the only that could work fast enough and has ISA slots. Than I get back to LOR problem and solve it, I guess I'll have to write some FAQ that will help to track down LORs. Thanks to all for replies! Now I have some ideas to move on. rik
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