Disc write activity timeline looks like the following:
CHECKPOINT -> Large disc write (30-40M/s), 1 second -> 4-5 seconds: no read and write activity at all, but server works slow -> 2-3 seconds: disc write activity about 4-5 M/s -> restore normal speed On 3/28/07, Dmitry Koterov <[EMAIL PROTECTED]> wrote:
New information. When I run CHECKPOINT manually in psql console, effect is fully reproduced. So - it is a checkpoint slowdown. The quesion is - how to make CHECKPOINT work faster? On 3/27/07, Dmitry Koterov <[EMAIL PROTECTED]> wrote: > > How to tune them? > > Now I have: > > checkpoint_segments = 5 # in logfile segments, min 1, 16MB each > checkpoint_timeout = 900 # range 30-3600, in seconds > checkpoint_warning = 30 # in seconds, 0 is off > > No checkpoint warnings in pgsql logs. > > > On 3/27/07, Oleg Bartunov < oleg@sai.msu.su> wrote: > > > > hmm, > > > > looks like checkpoint ? > > Check checkpoint settings in postgresql.conf. > > > > > > Oleg > > On Tue, 27 Mar 2007, Dmitry Koterov wrote: > > > > > Hello. > > > > > > I have found that sometimes heavy loaded PostgreSQL begins to run > > all the > > > queries slower than usual, sometimes - 5 and more times slower. I > > cannot > > > reprocude that, but symptoms are the following: queries work very > > fast for > > > 5-10 minutes, and after that - significant slowdown (every query, > > even a > > > simple one, works 5-10 and ever more times slower), disk write > > activity > > > grows too (but not everytime - I don't know exactli if there is a > > direct > > > correlation). 2-3 seconds, then - performance restores back to > > normal. > > > > > > Autovacuum is turned off. > > > > > > Machine has 2 processors, huge memory, fast SCSI disks. > > > > > > I understand that there is too less information. Please advice what > > to > > > monitor for better problem discovering. > > > > > > > Regards, > > Oleg > > _____________________________________________________________ > > Oleg Bartunov, Research Scientist, Head of AstroNet ( www.astronet.ru > > ), > > Sternberg Astronomical Institute, Moscow University, Russia > > Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/<http://www.sai.msu.su/%7Emegera/> > > phone: +007(495)939-16-83, +007(495)939-23-83 > > > > ---------------------------(end of > > broadcast)--------------------------- > > TIP 1: if posting/reading through Usenet, please send an appropriate > > subscribe-nomail command to [EMAIL PROTECTED] so that > > your > > message can get through to the mailing list cleanly > > > >
