Re: [RFC, POC] Don't require a NBuffer sized PrivateRefCount array of local buffer pins

On 2014-08-26 20:44:32 -0500, Jim Nasby wrote:
> These results look very encouraging, especially thinking about the
> cache impact.

Yep. I've seen PrivateRefCount array accesses prominently in the source
of cache misses in big servers.

> It occurs to me that it'd also be nice to have some
> stats available on how this is performing; perhaps a dtrace probe for
> whenever we overflow to the hash table, and one that shows maximum
> usage for a statement? (Presumably that's not much extra code or
> overhead...)

I don't use dtrace, so *I* won't do that. Personally I just dynamically
add probes using "perf probe" when I need to track something like this.

I don't see how you could track maximum usage without more
compliations/slowdowns than warranted.

Greetings,

Andres Freund

-- Andres Freund	                   http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services