Re: 2nd Level Buffer Cache

Josh Berkus wrote:
>
> > Was it really all that bad? IIRC we replaced ARC with the current clock
> > sweep due to patent concerns. (Maybe there were performance concerns as
> > well, I don't remember).
>
> Yeah, that was why the patent was frustrating. Performance was poor and
> we were planning on replacing ARC in 8.2 anyway. Instead we had to
> backport it.

[ Replying late.]

FYI, the performance problem was that while ARC was slightly better than
clock sweep in keeping useful buffers in the cache, it was terrible when
multiple CPUs were all modifying the buffer cache, which is why we were
going to remove it anyway.

In summary, any new algorithm has to be better at keeping useful data in
the cache, and also not slow down workloads on multiple CPUs.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ It's impossible for everything to be true. +