Re: kern/78474 for 5.4? (kernel stack swapout problem again)

From: John Baldwin <jhb_at_FreeBSD.org>
Date: Wed, 27 Apr 2005 14:10:00 -0400
On Friday 22 April 2005 11:37 pm, David Xu wrote:
> Doug White wrote:
> >On Thu, 21 Apr 2005, David Xu wrote:
> >>Sam Lawrance wrote:
> >>>Will this problem:
> >>>
> >>>Swapped out procs not brought in immediately after child exits
> >>>http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/78474
> >>>
> >>>be dealt with for the release of 5.4?
> >>>
> >>>Perhaps I'm the only FreeBSD user with swapped out processes ;-)
> >>>
> >>>-Sam
> >>
> >>I have noticed that current spinlock implementation no longer means that
> >>CPU must be in critical region (critical_enter is called), even previous
> >>hack TDP_WAKEPROC0 is no longer correct, :(, I think it is the time to
> >>disable swapout.
> >
> >I'm sorry, I can't parse your double negative.  On -CURRENT critical
> >sections (entered with critical_enter()) no longer disable interrupts, but
> >do inhibit preemption.  But spinlocks still do critical_enter() (see
> >spinlock_enter()).
>
> I will commit the patch provided in the PR, it should work. I am just
> worrying
> TDP_WAKEPROC0 will not work if spinlock does not entering critical region.

Read what Doug wrote.  spinlock_enter() still calls critical_enter(), so all 
spin locks still contain critical sections.

-- 
John Baldwin <jhb_at_FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org
Received on Wed Apr 27 2005 - 16:45:52 UTC

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