Re: Weird one

Make sure you do a checkpoint between runs. Whenever you drop a table (which includes truncate), the extents dropped can and will be picked up by some other table. Until a checkpoint occurs, any insert into the tables on those dbspaces will have to be plogged. LRU's kicking in? On Sep 24, 5:51 pm, "Art Kagel" <art.ka...@gmail.com> wrote: > <Cross posted to CDI & IDS Forum> > > OK, an oddity for you.  I'm doing some performance and tuning testing using > multiple copies of dbload. > > I'll tell you what I'm dealing with.  Anyone with any idea as to why the > engine is behaving as it is please pipe in. > > Platform: Linux 2.6.9-67.ELsmp, x86-32 with 2 single core 3.4GHZ processors, > single disk spindle for IDS another for the OS > IDS Vers:  10.00.UC8 > > OK, so I'm getting reasonable timings running various numbers of load > clients against the engine with 1, 2, 4, 6, & 8 CPU VPs truncating the table > between runs. > > I notice in TOP that at some point in the run IO Wait goes way up and CPU > consumption way down for 10-30 seconds then back to 'normal'.  I figure, > "Oh!  Extends are being added."  So after completing the set of timing runs > I change the script to drop and recreate the table with an extent size > sufficient for the loaded data in the initial load instead of the truncate > and run the tests again expecting to see that the runtimes have decrease by > 10-20 seconds per run.  NO! the runtimes INCREASED by 16 to 64 seconds! > > Yes, I checked that there was indeed still a single extent the size of the > initial extent size allocation after each load. > > Any ideas as to why this should be? > > -- > Art S. Kagel > Oninit (www.oninit.com) > IIUG Board of Directors (a...@iiug.org) > > Disclaimer: Please keep in mind that my own opinions are my own opinions and > do not reflect on my employer, Oninit, the IIUG, nor any other organization > with which I am associated either explicitly or implicitly. Neither do those > opinions reflect those of other individuals affiliated with any entity with > which I am affiliated nor those of the entities themselves.