Re: [PATCH 0/8][RFC] IO latency/throughput fixes

[Mike Galbraith]

On Tue, 2009-04-07 at 07:33 -0700, Linus Torvalds wrote:
> 
> On Tue, 7 Apr 2009, Mark Lord wrote:
> > 
> > What happens with ext3 "writeback", and ext4 "whatever",
> > when one does the quickie reboot method:
> > 
> >   ALT-SYSRQ-S ALT-SYSRQ-U ALT-SYSRQ-S ALT-SYSRQ-B
> > 
> > ???
> 
> Since 's' syncs (I think 'u' does too, as part of making things 
> read-only), the data blocks will be on disk after the boot regardless of 
> any other ordering.
> 
> Of course, it will leave all your lock-files files alone, and I can almost 
> guarantee that some daemons (read: "NetworkManager") will then fail on the 
> next boot because they think they are already running.

I don't do that _regularly_, but have had cause to do so many times over
the last couple years since switching to data=writeback.  Box boots up
fine here, at least with opensuse 10.3 and 11.0 it does.

I've had to reconfigure evolution, and some desktop settings a few times
after pulling the _eject_ handle (plain sysrq-b or BRB if kernel is
having a bad hair day), but that's about it.

	-Mike

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