On Tue, 2007-05-15 at 10:42 +0100, Heikki Linnakangas wrote:
> Luke Lonergan wrote:
> > 32 buffers = 1MB with 32KB blocksize, which spoils the CPU L2 cache
> > effect.
> >
> > How about using 256/blocksize?
>
> Sounds reasonable. We need to check the effect on the synchronized
> scans, though.
>
I am a little worried that there will be greater differences in position
as the number of scans increase. If we have only 8 buffers and several
scans progressing, will they all be able to stay within a few buffers of
eachother at any given time?
Also, with 8 buffers, that means each scan must report every 4 pages at
most (and maybe every page), which increases lock contention (the new
design Heikki and I discussed requires a lock every time a backend
reports its position).
Regards,Jeff Davis