Date: Thu, 17 Nov 2011 11:37:18 -0500 From: John Baldwin <jhb@freebsd.org> To: Andriy Gapon <avg@freebsd.org> Cc: Kostik Belousov <kostikbel@gmail.com>, Alexander Motin <mav@freebsd.org>, freebsd-current@freebsd.org Subject: Re: Stop scheduler on panic Message-ID: <201111171137.18663.jhb@freebsd.org> In-Reply-To: <4EC4D83E.3090307@FreeBSD.org> References: <20111113083215.GV50300@deviant.kiev.zoral.com.ua> <4EC4C712.8040701@FreeBSD.org> <4EC4D83E.3090307@FreeBSD.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On Thursday, November 17, 2011 4:47:42 am Andriy Gapon wrote:
> on 17/11/2011 10:34 Andriy Gapon said the following:
> > on 17/11/2011 10:15 Kostik Belousov said the following:
> >> I have the following change for eons on my test boxes. Without it,
> >> I simply cannot get _any_ dump.
> >>
> >> diff --git a/sys/cam/cam_xpt.c b/sys/cam/cam_xpt.c
> >> index 10b89c7..a38e42f 100644
> >> --- a/sys/cam/cam_xpt.c
> >> +++ b/sys/cam/cam_xpt.c
> >> @@ -4230,7 +4230,7 @@ xpt_done(union ccb *done_ccb)
> >> TAILQ_INSERT_TAIL(&cam_simq, sim, links);
> >> mtx_unlock(&cam_simq_lock);
> >> sim->flags |= CAM_SIM_ON_DONEQ;
> >> - if (first)
> >> + if (first && panicstr == NULL)
> >> swi_sched(cambio_ih, 0);
> >> }
> >> }
> >
> > I think that this (or similar) change should go into the patch and the tree.
> >
>
> And, BTW, I still would like to do something like the following (perhaps with
> td_oncpu = NOCPU and td_flags &= ~TDF_NEEDRESCHED also moved to the common code):
>
> Index: sys/kern/sched_ule.c
> ===================================================================
> --- sys/kern/sched_ule.c (revision 227608)
> +++ sys/kern/sched_ule.c (working copy)
> @@ -1790,7 +1790,6 @@ sched_switch(struct thread *td, struct thread *new
> td->td_oncpu = NOCPU;
> if (!(flags & SW_PREEMPT))
> td->td_flags &= ~TDF_NEEDRESCHED;
> - td->td_owepreempt = 0;
> tdq->tdq_switchcnt++;
> /*
> * The lock pointer in an idle thread should never change. Reset it
> Index: sys/kern/kern_synch.c
> ===================================================================
> --- sys/kern/kern_synch.c (revision 227608)
> +++ sys/kern/kern_synch.c (working copy)
> @@ -406,6 +406,8 @@ mi_switch(int flags, struct thread *newtd)
> ("mi_switch: switch must be voluntary or involuntary"));
> KASSERT(newtd != curthread, ("mi_switch: preempting back to ourself"));
>
> + td->td_owepreempt = 0;
> +
> /*
> * Don't perform context switches from the debugger.
> */
> Index: sys/kern/sched_4bsd.c
> ===================================================================
> --- sys/kern/sched_4bsd.c (revision 227608)
> +++ sys/kern/sched_4bsd.c (working copy)
> @@ -940,7 +940,6 @@ sched_switch(struct thread *td, struct thread *new
> td->td_lastcpu = td->td_oncpu;
> if (!(flags & SW_PREEMPT))
> td->td_flags &= ~TDF_NEEDRESCHED;
> - td->td_owepreempt = 0;
> td->td_oncpu = NOCPU;
>
> /*
>
> Does anybody see any potential problems with such a change?
Hmm, does this mean the preemption will be lost if you break into the
debugger and continue in the non-panic case?
--
John Baldwin
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201111171137.18663.jhb>