Re: [PATCH wq/for-3.19 3/3] workqueue: dump workqueues on sysrq-t

Re: [PATCH wq/for-3.19 3/3] workqueue: dump workqueues on sysrq-t

[Greg Kroah-Hartman]

On Mon, Dec 08, 2014 at 02:22:29PM -0500, Tejun Heo wrote:
> (cc'ing Greg for tty)
> 
> On Mon, Dec 08, 2014 at 11:05:15AM -0800, Andrew Morton wrote:
> > > Believe it or not, we already used up all alphanumerics if we count in
> > > the arch-specific ones.  Given that the workqueue information would
> > > primarily be useful in tracking down hangs and we'd want to see the
> > > dump of tasks in that case anyway, sysrq-t isn't a bad fit for
> > > appending workqueue dump.  If anybody has a better idea, I'm all ears.
> > 
> > Really.  Upper case?
> 
> Greg, would using uppercase chars for sysrq work over the different
> types of ttys?

I'm dragging in linux-serial@vger here also, but I think uppercase
characters will work from a tty standpoint.  I don't know about keyboard
scancodes, if they will do "odd" things wanting a shift with the sysrq
key at the same time.

Oh wait, I think that might be it, shift is needed for the sysrq key on
the keyboard to start with, right?  So there probably isn't a way to
test the difference of a lower/upper case key here.

I'm traveling this week, and don't have access to a "real" keyboard at
the moment, but this should be pretty easy for someone to test who has
one and cares about this type of thing {hint}.

thanks,

greg k-h

Re: [PATCH wq/for-3.19 3/3] workqueue: dump workqueues on sysrq-t

[Tejun Heo]

Hello, Greg.

On Tue, Dec 09, 2014 at 11:50:57PM -0500, Greg Kroah-Hartman wrote:
> Oh wait, I think that might be it, shift is needed for the sysrq key on
> the keyboard to start with, right?  So there probably isn't a way to

On x86, the combo is alt-sysrq, so shift can theoretically be added.

> test the difference of a lower/upper case key here.
> 
> I'm traveling this week, and don't have access to a "real" keyboard at
> the moment, but this should be pretty easy for someone to test who has
> one and cares about this type of thing {hint}.

Just tested on a PS/2 port attached keyboard and it doesn't go
through.  I'm not sure where this is getting lost but given that
people sometimes have to use ctrl too to invoke sysrq, throwing in
shift makes it a four key combo which is likely to be over the
rollover capabilities of most keyboards.  It doesn't seem like a good
path to follow to me.  :(

Thanks.

-- 
tejun