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From: torvalds@transmeta.com (Linus Torvalds)
Subject: Re: [Lse-tech] Re: RFC: patch to allow lock-free traversal of lists with insertion
Date: Wed, 10 Oct 2001 05:05:10 +0000 (UTC)
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In article <20011010040502.A726@athlon.random>,
Andrea Arcangeli  <andrea@suse.de> wrote:
>On Tue, Oct 09, 2001 at 08:45:15AM -0700, Paul McKenney wrote:
>> Please see the example above.  I do believe that my algorithms are
>> reliably forcing proper read ordering using IPIs, just in an different
>> way.  Please note that I have discussed this algorithm with Alpha
>> architects, who believe that it is sound.
>
>The IPI way is certainly safe.

Now, before people get all excited, what is this particular code
actually _good_ for?

Creating a lock-free list that allows insertion concurrently with lookup
is _easy_.

But what's the point? If you insert stuff, you eventually have to remove
it. What goes up must come down. Insert-inane-quote-here.

And THAT is the hard part. Doing lookup without locks ends up being
pretty much worthless, because you need the locks for the removal
anyway, at which point the whole thing looks pretty moot.

Did I miss something?

		Linus
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