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

Sam Lawrance boris at brooknet.com.au
Fri Apr 22 20:46:15 PDT 2005


On Sat, 2005-04-23 at 11:37 +0800, 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.

If it's any comfort, using that patch, I've not had any swap-in delay
problems since i raised the PR in early March.  Running with all the
typical debugging options turned on, and no problems arose.

-Sam





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