Re: [Testperf-general] Re: First set of OSDL Shared Memscalability

Tom Lane wrote:
> > I've been thinking about implementing a scheme that helps you decide how
> > big the shared_buffers SHOULD BE, by making the LRU list bigger than the
> > cache itself, so you'd be able to see whether there is beneficial effect in
> > increasing shared_buffers.
>
> ARC already keeps such a list --- couldn't you learn what you want to
> know from the existing data structure? It'd be fairly cool if we could
> put out warnings "you ought to increase shared_buffers" analogous to the
> existing facility for noting excessive checkpointing.

Agreed. ARC already keeps a list of buffers it had to push out recently
so if it needs them again soon it knows its sizing of recent/frequent
might be off (I think). Anyway, such a log report would be super-cool,
say if you pushed out a buffer and needed it very soon, and the ARC
buffers are already at their maximum for that buffer pool.

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