It would be nice to keep the gettimeofday()s wherever they are most useful on hardware/software where they are cheap. Perhaps a compile-time option?
On Fri, June 9, 2006 11:18 am, Martijn van Oosterhout wrote: > On Fri, Jun 09, 2006 at 10:00:20AM -0400, Tom Lane wrote: > >> To tell you the truth, this information makes me even less pleased with >> the sampling-gettimeofday patch than I was before. If gettimeofday() >> in itself increases the runtime of a node by a factor of 10, then just >> trying to subtract off that time is no solution. There's too much >> impact on surrounding nodes, and too much roundoff error anyhow. I had >> thought we were applying an order-of-ten-percent correction by >> subtracting SampleOverhead, not an order-of-10x correction :-( > > Eh? The whole point is to call gettimeofday() much less often. If you > call it 1000th as often, then the correction is only on the order of one > hundredth of the normal query time... > > Subtracting SampleOverhead is only a correction on the order of a few > percent, it's the reduced calling of gettimeofday() that provides the > benefit. > > Have a nice day, > -- > Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/ > >> From each according to his ability. To each according to his ability to >> litigate. > ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings