Date: Wed, 29 Nov 2006 15:51:06 -0700 From: Scott Long <scottl@samsco.org> To: John Birrell <jb@what-creek.com> Cc: Rene Ladan <r.c.ladan@gmail.com>, jb@freebsd.org, freebsd-current@freebsd.org Subject: Re: calcru-triggered panic? Message-ID: <456E0EDA.60603@samsco.org> In-Reply-To: <20061129225025.GA584@what-creek.com> References: <45622068.2050705@student.tue.nl> <200611291204.03716.jhb@freebsd.org> <20061129223221.GA359@what-creek.com> <456E0C66.4060404@samsco.org> <20061129225025.GA584@what-creek.com>
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John Birrell wrote: > On Wed, Nov 29, 2006 at 03:40:38PM -0700, Scott Long wrote: >> It's probably less of an issue now that it used to be, since I/O is >> decoupled through GEOM threads. In 4.x, you could have a stack that >> went from the syscall, through VFS, UFS, the block layer, CAM, and >> finally the device driver. When I was working on RAIDFrame, adding >> just a couple hundred bytes of stack usage would cause it to blow out. >> But as I said, it might not be as much of an issue now. > > Is it possible to check how deep the stack is and avoid using a stack > buffer if too deep? > > -- > John Birrell I don't know how to do it in a platform-independent way. For i386, I'd check %esp and see if it's getting close to a 2x page boundary. Scott
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