On Fri, 2009-08-14 at 14:00 -0400, Jeremy Carroll wrote: > I am confused about what the OS is reporting for memory usage on > CentOS 5.3 Linux. Looking at the resident memory size of the > processes. Looking at the resident size of all postgres processes, the > system should be using around 30Gb of physical ram. I know that it > states that it is using a lot of shared memory. My question is how to > I determine how much physical RAM postgres is using at any point in > time? > > This server has 24Gb of ram, and is reporting that 23GB is free for > use. See calculation below > > (Memory Total – Used) + (Buffers + Cached) = Free Memory > (24675740 – 24105052) + (140312 + 22825616) = 23,536,616 or ~23 > Gigabytes > you're using cached swap in your calculation ( 22825616 ) swap is not RAM -- it's disk > > So if my server has 23Gb of ram that is free for use, why is postgres > reporting resident sizes of 30GB? Shared memory is reporting the same > values, so how is the OS reporting that only 1Gb of RAM is being used? you have 570688k free RAM + 140312k buffers RAM This looks to me like the OS is saying that you are using 24105052k used > > Help? > > top - 12:43:41 up 2 days, 19:04, 2 users, load average: 4.99, 4.81, > 4.33 > Tasks: 245 total, 4 running, 241 sleeping, 0 stopped, 0 zombie > Cpu(s): 26.0%us, 0.0%sy, 0.0%ni, 73.9%id, 0.1%wa, 0.0%hi, 0.0% > si, 0.0%st > Mem: 24675740k total, 24105052k used, 570688k free, 140312k > buffers > Swap: 2097144k total, 272k used, 2096872k free, 22825616k > cached > --------------------- > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ > COMMAND > 19469 postgres 15 0 8324m 7.9g 7.9g S 0.0 33.7 0:54.30 postgres: > writer process > > 29763 postgres 25 0 8329m 4.5g 4.5g R 99.8 19.0 24:53.02 postgres: > niadmin database x.x.x.49(51136) UPDATE > 29765 postgres 25 0 8329m 4.4g 4.4g R 99.8 18.8 24:42.77 postgres: > niadmin database x.x.x.49(51138) UPDATE > 31778 postgres 25 0 8329m 4.2g 4.2g R 99.5 17.8 17:56.95 postgres: > niadmin database x.x.x.49(51288) UPDATE > 31779 postgres 25 0 8329m 4.2g 4.2g R 99.1 17.8 17:59.62 postgres: > niadmin database x.x.x.49(51289) UPDATE > 31780 postgres 23 0 8329m 4.1g 4.1g R 100.1 17.5 17:52.53 > postgres: niadmin database x.x.x.49(51290) UPDATE > 19467 postgres 15 0 8320m 160m 160m S 0.0 0.7 > 0:00.24 /opt/PostgreSQL/8.3/bin/postgres > -D /opt/PostgreSQL/8.3/data > 19470 postgres 15 0 8324m 2392 1880 S 0.0 0.0 0:01.72 postgres: > wal writer process -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
