On Mon, Mar 5, 2012 at 4:04 PM, Tom Lane <tgl@xxxxxxxxxxxxx> wrote: > Mike C <smith.not.western@xxxxxxxxx> writes: >> I have been using table 17-2, Postgres Shared Memory Usage >> (http://www.postgresql.org/docs/9.1/interactive/kernel-resources.html) >> to calculate approximately how much memory the server will use. I'm >> using Postgres 9.1 on a Linux 2.6 (RHEL 6) 64bit system, with 8GB RAM. >> Database is approximately 5GB, and is a mixture of read/write. >> Postgres is occasionally being killed by the linux oom-killer. I am >> trying to understand how much memory postgres could use, and how to >> change the configuration to bring it down to a level that won't get it >> killed. > > Basically, you can't fix it that way, at least not if you want to have a > sane configuration. The problem is misdesign of the OOM killer: it will > count the shared memory block against the postmaster *once for each > child process*. The only realistic solution is to turn off OOM kill for > the postmaster (and maybe its children too, or maybe you'd rather have > them immune as well). The former is pretty easy to do if you're > launching the postmaster from a root-privileged initscript. I think > most prepackaged versions of PG are set up to be able to do this > already. If you want the children OOM-killable it requires a > source-code tweak as well, since that property is normally inherited. Ok, that makes sense. With regards to work_mem, am I right in thinking the child processes only allocate enough memory to meet the task at hand, rather than the full 16M specified in the config file? > But anyway, your calculations are totally off: > >> Shared Disk Buffers = 36,077,725,286,400 >> = (block_size + 208) * shared_buffers >> = (8192 + 208) * 4294967296 >> = ~33TB > > I think you've multiplied by the block size one time too many. Ditto > for WAL buffers. Yes spot on, removed the block_size and it is now the more sane ~4.1GB. Thanks for your help, Mike -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
