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Date: Thu, 3 Mar 2005 01:42:06 -0500
From: David Schultz <das@FreeBSD.ORG>
To: Mike Silbersack <silby@silby.com>
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Subject: Re: cvs commit: src/sys/kern kern_sig.c
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On Thu, Mar 03, 2005, Mike Silbersack wrote:
> 
> On Thu, 3 Mar 2005, David Schultz wrote:
> 
> >Of course, there's another possible solution which is to remove
> >the swapping code entirely.  That would certainly simplify things,
> >but it would also make FreeBSD degrade less gracefully under load.
> 
> I don't think that would be a big loss; by the time you're doing a lot of 
> process swapping, you're pretty screwed.
> 
> A process has to be swapped back in in order for it to be killed, right? 
> We might be better off without swapping, in that case.

Yeah, with 16K kernel stacks, you'd have to swap a lot of threads
to make a big difference in the amount of wired memory in the
system.  KSE helps with this, because processes with thousands of
user threads don't have thousands of kernel threads.

Another thing that swapping does, though, is prevent some
processes from running for a while when the system is under load,
thereby reducing contention for resources and allowing the other
processes to get things done.  If people decide to go this way, it
might be a good idea to keep the second feature.  It costs very
little in terms of complexity because no actual swapping is done.
But who knows?  Maybe nobody cares about this, either...