Hi -
On Thu, Jul 26, 2007 at 11:02:26AM -0400, Mathieu Desnoyers wrote:
> [...]
> > > The problem is also in _stp_print_flush, not *only* in relay code:
> > > void _stp_print_flush (void)
> > > ...
> > > spin_lock(&_stp_print_lock);
> > > spin_unlock(&_stp_print_lock);
> > >
> > > Those will turn into mutexes with -rt.
> >
> > Indeed,
(Though actually that bug was fixed some time ago.)
> > plus systemtap-generated locking code uses rwlocks,
> > local_irq_save/restore or preempt_disable, in various places. Could
> > someone point to a place that spells out what would be more
> > appropriate way of ensuring atomicity while being compatible with -rt?
>
> AFAIK, for your needs either:
> [...]
> - Use per-cpu data with preempt disabling/irq disabling
As in local_irq_save / preempt_disable? Yes, already done.
> - Use the original "real" spin locks/rwlocks (raw_*).
> [...]
It was unclear from the OLS paper whether the spin_lock_irq* family of
functions also had to be moved to the raw forms.
> You just don't want to sleep in the tracing code. [...] Since you
> will likely disable preemption, make sure your tracing code executes
> in a deterministic time.
Definitely, that has always been the case.
> Make sure that the sub-buffer switch code respects that too [...]
We will review that part of the related code.
- FChE
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
