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 <dmitry@xxxxxxxxxx> 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 <dmitry@xxxxxxxxxx> 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@xxxxxxxxxx> 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@xxxxxxxxxx, http://www.sai.msu.su/~megera/
phone: +007(495)939-16-83, +007(495)939-23-83
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