Date: Wed, 19 Apr 2006 21:20:10 -0400 From: Kurt Miller <kurt@intricatesoftware.com> To: freebsd-java@freebsd.org Cc: Carl Johan Gustavsson <carl.gustavsson@bahnhofbredband.se> Subject: Re: Diablo 1.5 SIGBUS - fixed Message-ID: <200604192120.10697.kurt@intricatesoftware.com> In-Reply-To: <4446BE1A.6070101@bahnhofbredband.se> References: <C05FF5D0.246B%odela01@ca.com> <200604101315.12391.lists@intricatesoftware.com> <4446BE1A.6070101@bahnhofbredband.se>
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On Wednesday 19 April 2006 6:47 pm, Carl Johan Gustavsson wrote: > Kurt Miller wrote: > > The SIGBUS occurred in a thread related optimization for > > multiprocessor systems that Sun introduced after the initial > > release of 1.5.0. From what I can gather from a brief > > inspection of the code is that they were removing unnecessary > > memory barriers, but added the UseMembar option to have a > > way to enable them again. The SIGBUS was happening in the > > new optimized code path that didn't use a membar. > > > > The best description I've found so far on the use of > > membar is in this old bug report: > > > > http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4629468 > > > > The following excerpt was the most relevant, "For MP systems, > > a membar may still be required so that the load or store is seen > > in the order desired across a machine's memory system. It depends > > on the memory system." > > > > In other bug reports I see that on Windows for the 1.5.0_0x > > releases -XX:+UseMembar is the default because of problems with > > the changes. So diablo on multiprocessor systems will need to use > > -XX:+UseMembar until the next release where it can be made the > > default. > > How can I make this option default? I'm using 6.1-PRE. I guess you could add it to the /usr/local/bin/javavm script. -Kurt
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