Re: Questions on query planner, join types, and work_mem

Hannu Krosing  wrote:
 
> This seems to indicate about 1 ms for moving pages over
> user/system boundary. (Intel Core2 Duo T7500 @ 2.20GHz, Ubuntu
> 9.10, 4GB RAM)
 
Using Greg's test script on a box with two cores like this:
 
Intel(R) Pentium(R) D CPU 3.40GHz
Linux kgrittn-desktop 2.6.31-22-generic #60-Ubuntu SMP Thu May 27
00:22:23 UTC 2010 i686 GNU/Linux
 
Dividing the run time by accumulated buffers_backend, it comes to
less than 0.2 ms per dirty buffer flushed.  If I get a few spare
ticks I'll try again while checking what vmstat and oprofile say
about how much of that went to things besides the transfer from
shared buffers to the OS.  I mean, it's possible I was waiting on
actual disk I/O at some point.
 
-Kevin