Re: I need an unused bit in the bidirectionnal layout object

On Thu, 2005-03-03 at 13:48 -0500, Etienne Gagnon wrote:
> Chris Pickett wrote:
> > It is acceptable to reduce the recursive count field size from 5 bits to
> > 4 bits -- this just means locks can't be reentered as many times before
> > expanding -- but this happens rarely in any event.  Just find some bit
> > to use, and later you can worry about the most efficient tradeoff to make.
> 
> Agreed. :-)

Actually Bacon [*] (and others in their publications) show that locking
beyond 3 or at worst 4 recursions almost does not happen.  So if for
some reason you wanted to steal yet another bit and make recursions
counter 3 bit (which will hold info of up to 7 recursions) feel free.

				GBP

[*] See page 6 of this presentation
http://www.research.ibm.com/people/d/dfb/talks/Bacon98ThinTalk.pdf
or the paper itself
http://www.research.ibm.com/people/d/dfb/papers/Bacon98Thin.pdf

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