Re: Performance question (stripped down the problem) - Mailing list pgsql-general
From | Justin Clift |
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Subject | Re: Performance question (stripped down the problem) |
Date | |
Msg-id | 3BAA17E7.77C8BF47@postgresql.org Whole thread Raw |
In response to | Re: Performance question (stripped down the problem) ("Tille, Andreas" <TilleA@rki.de>) |
Responses |
Hardware tuning (Was: Performance question)
|
List | pgsql-general |
Hi Andreas, I'm running PostgreSQL 7.1.3 here on a PC with nearly a gig of ram, and running Linux Mandrake 8.0 First thing I did was to increase the amount of shared memory and stuff which Linux allows things to use : echo "kernel.shmall = 134217728" >> /etc/sysctl.conf echo "kernel.shmmax = 134217728" >> /etc/sysctl.conf For my system, that'll raise the shared memory limits to 128MB at system boot time. btw, the "134217728" figure = 128MB (128 * 1024 * 1024) Then I changed the limits for the running system (so no reboot is necessary) : echo 134217728 > /proc/sys/kernel/shmall echo 134217728 > /proc/sys/kernel/shmmax Then adjusted the postgresql.conf file with these values : sort_mem = 32768 shared_buffers = 220 Now, that's a bunch of shared_buffers, but at the same time I also raised the max_connections to 110. This seems to have dropped my execution times, but I haven't seriously gotten around to tuning this system. The key thing I think you've missed is to update the shared memory, etc. More info about it can be found at : http://www.postgresql.org/idocs/index.php?kernel-resources.html Bruce Momjian also put together some information about optimising things with PostgreSQL at : http://www.ca.postgresql.org/docs/hw_performance/ If you want to be able to benchmark things on your system, I use the "Open Source Database Benchmark" (Linux only at present), running the latest CVS version of it, and also tweaked to not use hash indices. A tarball of working source code is available at : http://techdocs.postgresql.org/techdocs/perftuningfigures.php Hope this is of assistance Andreas. Regards and best wishes, Justin Clift "Tille, Andreas" wrote: > > On Thu, 20 Sep 2001, Justin Clift wrote: > > > Sorry, I haven't seen the history of this thread. One question which > > might be relevant is, have you adjusted the postgresql.conf file from > > the default memory settings to be something better? > I adjusted two parameters: > > shared_buffers = 2048 > (When I tried 4096 I´ve got a connection error. Don´t know what this > means, but anyway increasing of this value did not changed anything.) > > sort_mem = 2048 > (After increasing this value (from default 512) to 1024 I got an > increase in speed from 20s to 18s - not much but better than nothing. > Further increase to 2048 did not change anything further so I stopped > here.) > > > If these are the times you're getting from a default configuration, you > > might be able to get far better results by doing performance tuning of > > PostgreSQL and/or the server. > Any other values which might help here? > > Kind regards > > Andreas. > > ---------------------------(end of broadcast)--------------------------- > TIP 4: Don't 'kill -9' the postmaster -- "My grandfather once told me that there are two kinds of people: those who work and those who take the credit. He told me to try to be in the first group; there was less competition there." - Indira Gandhi
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