Re: Scheduler: SIGSTOP on multi threaded processes

[Richard B. Johnson]

On Wed, 4 May 2005, Alex Riesen wrote:

> On 5/4/05, Daniel Jacobowitz <dan@xxxxxxxxxx> wrote:
> > On Wed, May 04, 2005 at 02:16:24PM -0400, Richard B. Johnson wrote:
> > > The kernel doesn't do SIGSTOP or SIGCONT. Within init, there is
> > > a SIGSTOP and SIGCONT handler. These can be inherited by others
> > > unless changed, perhaps by a 'C' runtime library. Basically,
> > > the SIGSTOP handler executes pause() until the SIGCONT signal
> > > is received.
> > >
> > > Any delay in stopping is the time necessary for the signal to
> > > be delivered. It is possible that the section of code that
> > > contains the STOP/CONT handler was paged out and needs to be
> > > paged in before the signal can be delivered.
> > >
> > > You might quicken this up by installing your own handler for
> > > SIGSTOP and SIGCONT....
> >
> > I don't know what RTOSes you've been working with recently, but none of
> > the above is true for Linux.  I don't think it ever has been.
>
> I don't even think it was true for anything. It's his usual way of
> saying things.

Nope, I thought he was talking about the terminal stopper/starter,
SIGTSTP used for X-ON and X-OFF. I thought he was sending that signal,
timing it, then restarting with SIGCONT. You can't restart or
even trap a SIGSTOP signal.


Cheers,
Dick Johnson
Penguin : Linux version 2.6.11 on an i686 machine (5537.79 BogoMips).
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