Re: Overhead for stats_command_string et al, take 2

Alvaro Herrera <alvherre@commandprompt.com> writes:
> Average of 5 runs, for the first two cases, on the x86 machine that
> shows high overhead in gettimeofday.

> I used only 30000 SELECT 1 queries instead of 100k.

> 30000 SELECT 1;
>                         HEAD            8.1
> no overhead             21.9            23.1    
> stats_command_string=1  22.4            36.6

> BEGIN; 30000 SELECT 1; COMMIT;
>                         HEAD            8.1
> no overhead             19.1            20.3
> stats_command_string=1  19.4            30.3

> It can be observed that HEAD in the no overhead case is actually faster
> than 8.1 on this machine.

That's more or less what I would have hoped to find, because we're
always finding ways to squeeze out bits of overhead here and there.
I wonder why your results are different from what I got on my older
machine?  I'll have to break out oprofile again and try to see what's
happening there.
        regards, tom lane