Swapping over ggate?

[Pawel Jakub Dawidek]

On Wed, May 19, 2004 at 11:12:09AM -0500, Craig Boston wrote:
+> Just curoius if anybody has tried playing with swap over ggate?
+> 
+> I thought I'd be clever and try to use it as a better workaround for the vinum 
+> swap problem...  i.e. instead of running it through md(4) and a filesystem, 
+> do something like:
+> 
+> ggatel create /dev/vinum/swap
+> swapon /dev/ggate0
+> 
+> That seemed to attach just fine.  However, doing something like
+> 
+> dd if=/dev/zero of=/dev/null bs=256m count=2
+> 
+> to provoke some swapping caused the system to freeze.  It was kind of weird 
+> for a minute -- I could still ping it and switch windows in screen, but the 
+> shell wouldn't respond to any commands.  Eventually it stopped responding to 
+> pings altogether and the ssh connection died.  Seemed like a VM deadlock, but 
+> unfortunately I was remote at the time and couldn't try to break in to DDB at 
+> the console.
+> 
+> Funny thing was that after a reboot I did the same thing and it worked fine.  
+> If I'm able to reproduce the freeze again I'll try to get ps and backtrace 
+> and all that good stuff.

The biggest problem in your situation is that ggatel(8) works as a
userland process and I think there is a 100% deadlock when system is
trying to swap ggatel process out.

-- 
Pawel Jakub Dawidek                       http://www.FreeBSD.org
pjd at FreeBSD.org                           http://garage.freebsd.pl
FreeBSD committer                         Am I Evil? Yes, I Am!
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