On Thu, 03 Nov 2005 18:29:09 +0000 Simon Riggs <[EMAIL PROTECTED]> wrote:
> On Thu, 2005-11-03 at 08:03 -0800, Mark Wong wrote: > > On Tue, 01 Nov 2005 07:32:32 +0000 > > Simon Riggs <[EMAIL PROTECTED]> wrote: > > > Concerned about the awful checkpointing. Can you bump wal_buffers to > > > 8192 just to make sure? Thats way too high, but just to prove it. > > > > > > We need to rdeuce the number of blocks to be written at checkpoint. > > > > > > bgwriter_all_maxpages 5 -> 15 > > > bgwriter_all_percent 0.333 > > > bgwriter_delay 200 > > > bgwriter_lru_maxpages 5 -> 7 > > > bgwriter_lru_percent 1 > > > > > > shared_buffers set lower to 100000 > > > (which should cause some amusement on-list) > > > > > > Okay, here goes, all with the same source base w/ the lw.patch: > > > > http://www.testing.osdl.org/projects/dbt2dev/results/dev4-014/44/ > > only increased wal_buffers to 8192 from 2048 > > 3242 notpm > > That looks to me like a clear negative effect from increasing > wal_buffers. Try putting it back down to 1024. > Looks like we need to plug that gap. > > > http://www.testing.osdl.org/projects/dbt2dev/results/dev4-014/43/ > > only increased bgwriter_all_maxpages to 15, and bgwriter_lru_maxpages to 7 > > 3019 notpm (but more interesting graph) > > Man that sucks. What the heck is happening there? Hackers - if you > watching you should see this graph - it shows some very poor behaviour. > > I'm not happy with that performance at all.... any chance you could re- > run that exact same test to see if we can get that repeatably? > > I see you have > vm.dirty_writeback_centisecs = 0 > > which pretty much means we aren't ever writing to disk by the pdflush > daemons, even when the bgwriter is active. > > Could we set the bgwriter stuff back to default and try > vm.dirty_writeback_centisecs = 500 http://www.testing.osdl.org/projects/dbt2dev/results/dev4-014/47/ 3309 notpm > > http://www.testing.osdl.org/projects/dbt2dev/results/dev4-014/45/ > > Same as the previously listen run with hared_buffers lowered to 10000 > > 2503 notpm > > Sorry, that was 100,000 not 10,000. Oops! http://www.testing.osdl.org/projects/dbt2dev/results/dev4-014/46/ 2794 notpm > Looks like we need dates on the log_line_prefix so we can check the > logs. Oops again! I didn't check to make sure I had set this correctly before I ran the last two tests, I'll get on it. > ...not sure about the oprofile results. Seems to show CreateLWLocks > being as high as xlog_insert, which is mad. Either that shows startup > time is excessive, or it means the oprofile timing range is too short. > Not sure which. Yeah, we've seen this before. I think I'll have to try pulling the oprofile cvs code to see if there's any improvement. I've been working with oprofile-0.9.1. Mark ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
