Re: checkpointer continuous flushing

> Note that I'm not comparing to HEAD in the above tests, but with the new 
> options desactivated, which should be more or less comparable to current 
> HEAD, i.e. there is no sorting nor flushing done, but this is not strictly 
> speaking HEAD behavior. Probably I should get some figures with HEAD as well 
> to check the "more or less" assumption.

Just for answering myself on this point, I tried current HEAD vs patch v4 
with sort OFF + flush OFF: the figures are indeed quite comparable (see 
below), so although the internal implementation is different, the 
performance when both options are off is still a reasonable approximation 
of the performance without the patch, as I was expecting. What patch v4 
still does with OFF/OFF which is not done by HEAD is balancing writes 
among tablespaces, but there is only one disk on these tests so it does 
not matter.

tps & stddev full speed:
                            HEAD         OFF/OFF
 tiny 1 client          727 +- 227     221 +- 246 small 1 client         158 +- 316     158 +- 325 medium 1 client
 148 +- 285     157 +- 326 tiny 4 clients        2088 +- 786    2074 +- 699 small 4 clients        192 +- 648     188
+-560 medium 4 clients       220 +- 654     220 +- 648
 

percent of late transactions:
                            HEAD       OFF/OFF
 tiny 4 clients 100 tps      6.31        6.67 small 4c 100 tps           35.68       35.23 medium 4c 100 tps
37.38      38.00 tiny 4c 200 tps             9.06        9.10 small 4c 200 tps           51.65       51.16 medium 4c
200tps          51.35       50.20 tiny 4 clients 400 tps     11.4        10.5 small 4 clients 400 tps    66.4
67.6

-- 
Fabien.