Re: Low Budget Performance, Part 2

On Wed, 27 Nov 2002 14:19:22 -0500 in message <21018(dot)1038424762(at)sss(dot)pgh(dot)pa(dot)us>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> eric soroos <eric-psql(at)soroos(dot)net> writes:
> > Running pgbench with: scaling factor=1, # transactions = 100, and
> > #clients =1,2,3,5,10,15
>
> The scaling factor has to at least equal the max # of clients you intend
> to test, else pgbench will spend most of its time fighting update
> contention (parallel transactions wanting to update the same row).
>

Ok, with the scaling factor set at 20, the new results are more in line with expectations:

For 1-10 clients, IDE gets 25-30 tps, SCSI 40-50 (more with more clients, roughly linear).

The CPU was hardly working in these runs (~50% on scsi, ~20% on ide), vs nearly 100% on the previous run.

I'm suspect that the previous runs were colored by having the entire dataset in memory as well as the update contention.

eric