Re: Linux max on shared buffers?

On Thu, Jul 11, 2002 at 05:07:29PM +0900, Curt Sampson wrote:
> Let's walk through an example. I have four pages total for caching.
> Let's look at a read scenario based on two for postgres and two for the
> OS, and one for postgres and three for the OS. Pn is a postgres buffer
> and OSn is an OS buffer; the numbers below those show which disk blocks
> are in which caches. We'll use an LRU algorithm for both caches and read
> the blocks in this order: 1 2 3 2 1 2 3.

Hmm, what about OS's that swap shared memory to disk. Wouldn't that change
things somewhat? Probably more in favour of giving more memory to the OS.

The other possibility would be to use mmap instead. That way you avoid the
double buffering altogether. Do you have any ideas about that?

--
Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> There are 10 kinds of people in the world, those that can do binary
> arithmetic and those that can't.