Re: ARC patent

On Wed, 2005-01-19 at 16:25 +1100, Neil Conway wrote:
> On Tue, 2005-01-18 at 23:26 -0500, Tom Lane wrote:
> > Not yet --- I suggested it but didn't get any yeas or nays.  I don't
> > feel this is solely core's decision anyway ... what do the assembled
> > hackers think?
> 
> I'm not sure it's a great idea.

It's not, but may still be required. We should defer any changes for a
month, just to see if its feasible to do that.

> I think the proper fix for the ARC issue is an 8.0.x release with a new
> replacement policy. To avoid introducing instability into 8.0, we should
> obviously test the new buffer replacement policy *very* carefully.

Agreed.

I prefer a plan that, if required, back ports NewStrategy to 8.0.x than
one that hobbles 8.1, just in case.

> However, I think the ARC replacement should *not* be a fundamental
> change in behavior: the algorithm should still attempt to balance
> recency and frequency, to adjust dynamically to changes in workload, to
> avoid "sequential flooding", and to allow constant-time page
> replacement. 

Agreed: Those are the requirements. It must also scale better as well.

All of which have sufficient prior art that they could never be seen to
in-themselves form the basis of a patent.

> If such a patch were developed, I don't
> think it would be a herculean task to include it in an 8.0.x release
> after a lot of careful testing and code review.

Agreed.

-- 
Best Regards, Simon Riggs