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SubjectRe: is killing zombies possible w/o a reboot?
Date
On Wednesday 03 November 2004 17:03, Doug McNaught wrote:

> It was already mentioned in this thread that the bookkeeping required
> to clean up properly from such an abort would add a lot of overhead
> and slow down the normal, non-buggy case.
>
I am going to continue pursuing this at the risk of making a bigger fool of
myself than I already am, but I want to make sure that I understand the
issues - and I did read the message you are referring to.

I think what you are saying is that there is kind of a race condition here.
When something is on the wait queue, it has to be followed through to
completion. An interrupt could be received at any time, and if it's taken
off of the wait queue prematurely, it'll crash the kernel, because the
interrupt has no way of telling that.

That's fine as it goes, I understand that. But I submit that this is a
horrible design. I've been bitten by this more than once - usually regarding
broken NFS connections.

But what I don't understand is why the bookkeeping would be so inefficient.
It seems to me that all that would be required is a bitfield of some sort.
If that position in the qait queue becomes invalid, when the interrupt is
received to process it, the kernel notes that a flag is set invalidating that
part of the wait queue, dumps the output to dave null, and goes on to the
next. This doesn't seem inefficient to me, unless I'm missing something.
A little more inefficient, yes, but not to near the cost that seems to be
implied.

And I also have to ask this question: what is more inefficient, slowing down
processing of output waiting on the queue, or having to reboot when a process
gets stuck due to faulty drivers? At the very least, a compile option seems
like it would be worthwhile for those that would like this behavior.

And I probably am. Missing something, that is.

--Russell

> -Doug

--

Russell Miller - rmiller@duskglow.com - Le Mars, IA
Duskglow Consulting - Helping companies just like you to succeed for ~ 10 yrs.
http://www.duskglow.com - 712-546-5886
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