Обсуждение: Low values for cached size
Hi,
We're facing performance problems in a Linux box running CentOS release 5 (Final) and PostgreSQL 8.2.4. I've done some basic checks in the configuration but everything looks fine to me. One weird behaviour I've found is the cached size showed by the
"top" and "free" Linux commands:
"top" and "free" Linux commands:
top - 08:32:17 up 3 days, 19:04, 1 user, load average: 1.09, 1.07, 1.10
Tasks: 173 total, 2 running, 170 sleeping, 0 stopped, 1 zombie
Cpu(s): 9.5%us, 0.5%sy, 0.0%ni, 88.2%id, 1.7%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 3631900k total, 3378056k used, 253844k free, 25488k buffers
Swap: 4192956k total, 100k used, 4192856k free, 2356588k cached
[postgres@server01 etc]$ free
total used free shared buffers cached
Mem: 3631900 3174804 457096 0 14280 2086184
-/+ buffers/cache: 1074340 2557560
Swap: 4192956 108 4192848
[postgres@server01 etc]$
Both commands show values ranging from 2GB to 2.3GB for the cached size and the server has 3.5GB RAM. I do usally see cached values with sizes bearing the size of the RAM in other servers. It seams that something is consuming the RAM and not letting it free to be used as cache for Linux files, right?
The shared_buffers (256MB) is not high and I can not see a reason for this. Initially I've thought the problem was
because the system was running with runlevel 5, but now, it's running with runlevel 3 and even so the values for
cached size does not change.
because the system was running with runlevel 5, but now, it's running with runlevel 3 and even so the values for
cached size does not change.
Any suggestions or directions I could follow to discover the reason?
Reimer
--
Reimer
47-3457-0881 47-9183-0547 msn: carlosreimer@hotmail.com
skype: carlosreimer
On Fri, Sep 25, 2009 at 3:28 PM, Carlos Henrique Reimer <carlos.reimer@opendb.com.br> wrote: > Hi, > > We're facing performance problems in a Linux box running CentOS release 5 > (Final) and PostgreSQL 8.2.4. I've done some basic checks in the > configuration but everything looks fine to me. One weird behaviour I've > found is the cached size showed by the > "top" and "free" Linux commands: > > top - 08:32:17 up 3 days, 19:04, 1 user, load average: 1.09, 1.07, 1.10 > Tasks: 173 total, 2 running, 170 sleeping, 0 stopped, 1 zombie > Cpu(s): 9.5%us, 0.5%sy, 0.0%ni, 88.2%id, 1.7%wa, 0.0%hi, 0.0%si, > 0.0%st > Mem: 3631900k total, 3378056k used, 253844k free, 25488k buffers > Swap: 4192956k total, 100k used, 4192856k free, 2356588k cached > > [postgres@server01 etc]$ free > total used free shared buffers cached > Mem: 3631900 3174804 457096 0 14280 2086184 > -/+ buffers/cache: 1074340 2557560 > Swap: 4192956 108 4192848 > [postgres@server01 etc]$ > > Both commands show values ranging from 2GB to 2.3GB for the cached size and > the server has 3.5GB RAM. I do usally see cached values with sizes bearing > the size of the RAM in other servers. It seams that something is consuming > the RAM and not letting it free to be used as cache for Linux files, right? > The shared_buffers (256MB) is not high and I can not see a reason for this. > Initially I've thought the problem was > because the system was running with runlevel 5, but now, it's running with > runlevel 3 and even so the values for > cached size does not change. > > Any suggestions or directions I could follow to discover the reason? If you run top, then hit M, and post the first 20 or so rows after what you have here I can take a guess.
Hi Scott,
The top and M option:
top - 20:37:52 up 8:19, 2 users, load average: 0.00, 0.00, 0.00
Tasks: 96 total, 1 running, 95 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.0%us, 0.2%sy, 0.0%ni, 99.5%id, 0.3%wa, 0.0%hi, 0.0%si, 0.0%st
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
4011 postgres 18 0 298m 276m 251m S 0 7.8 0:40.16 postgres
2950 postgres 15 0 271m 232m 231m S 0 6.6 0:01.06 postgres
2938 postgres 18 0 271m 7120 6748 S 0 0.2 0:00.31 postgres
3012 root 18 0 10852 5644 1588 S 0 0.2 0:00.01 miniserv.pl
2660 root 15 0 13448 4616 968 S 0 0.1 0:00.01 python
2732 ntp 15 0 4316 4316 3312 S 0 0.1 0:00.04 ntpd
2397 root 12 -3 10100 3860 2272 S 0 0.1 0:00.08 python
2870 haldaemo 18 0 5700 3724 1608 S 0 0.1 0:01.51 hald
5917 root 18 0 10424 2804 1388 S 0 0.1 0:00.00 httpd
5992 root 15 0 9000 2724 2204 S 0 0.1 0:00.03 sshd
5140 root 16 0 8996 2720 2204 S 0 0.1 0:00.04 sshd
5918 apache 23 0 10424 2084 632 S 0 0.1 0:00.00 httpd
5920 apache 23 0 10424 2084 632 S 0 0.1 0:00.00 httpd
5921 apache 23 0 10424 2084 632 S 0 0.1 0:00.00 httpd
5922 apache 23 0 10424 2084 632 S 0 0.1 0:00.00 httpd
5923 apache 25 0 10424 2084 632 S 0 0.1 0:00.00 httpd
5924 apache 25 0 10424 2084 632 S 0 0.1 0:00.00 httpd
5925 apache 25 0 10424 2084 632 S 0 0.1 0:00.00 httpd
5926 apache 25 0 10424 2084 632 S 0 0.1 0:00.00 httpd
2696 root 18 0 9676 1968 1360 S 0 0.1 0:00.00 cupsd
2757 root 15 0 9028 1860 776 S 0 0.1 0:00.00
Tasks: 96 total, 1 running, 95 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.0%us, 0.2%sy, 0.0%ni, 99.5%id, 0.3%wa, 0.0%hi, 0.0%si, 0.0%st
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
4011 postgres 18 0 298m 276m 251m S 0 7.8 0:40.16 postgres
2950 postgres 15 0 271m 232m 231m S 0 6.6 0:01.06 postgres
2938 postgres 18 0 271m 7120 6748 S 0 0.2 0:00.31 postgres
3012 root 18 0 10852 5644 1588 S 0 0.2 0:00.01 miniserv.pl
2660 root 15 0 13448 4616 968 S 0 0.1 0:00.01 python
2732 ntp 15 0 4316 4316 3312 S 0 0.1 0:00.04 ntpd
2397 root 12 -3 10100 3860 2272 S 0 0.1 0:00.08 python
2870 haldaemo 18 0 5700 3724 1608 S 0 0.1 0:01.51 hald
5917 root 18 0 10424 2804 1388 S 0 0.1 0:00.00 httpd
5992 root 15 0 9000 2724 2204 S 0 0.1 0:00.03 sshd
5140 root 16 0 8996 2720 2204 S 0 0.1 0:00.04 sshd
5918 apache 23 0 10424 2084 632 S 0 0.1 0:00.00 httpd
5920 apache 23 0 10424 2084 632 S 0 0.1 0:00.00 httpd
5921 apache 23 0 10424 2084 632 S 0 0.1 0:00.00 httpd
5922 apache 23 0 10424 2084 632 S 0 0.1 0:00.00 httpd
5923 apache 25 0 10424 2084 632 S 0 0.1 0:00.00 httpd
5924 apache 25 0 10424 2084 632 S 0 0.1 0:00.00 httpd
5925 apache 25 0 10424 2084 632 S 0 0.1 0:00.00 httpd
5926 apache 25 0 10424 2084 632 S 0 0.1 0:00.00 httpd
2696 root 18 0 9676 1968 1360 S 0 0.1 0:00.00 cupsd
2757 root 15 0 9028 1860 776 S 0 0.1 0:00.00
Thank you!
sendmail2009/9/25 Scott Marlowe <scott.marlowe@gmail.com>
If you run top, then hit M, and post the first 20 or so rows afterOn Fri, Sep 25, 2009 at 3:28 PM, Carlos Henrique Reimer
<carlos.reimer@opendb.com.br> wrote:
> Hi,
>
> We're facing performance problems in a Linux box running CentOS release 5
> (Final) and PostgreSQL 8.2.4. I've done some basic checks in the
> configuration but everything looks fine to me. One weird behaviour I've
> found is the cached size showed by the
> "top" and "free" Linux commands:
>
> top - 08:32:17 up 3 days, 19:04, 1 user, load average: 1.09, 1.07, 1.10
> Tasks: 173 total, 2 running, 170 sleeping, 0 stopped, 1 zombie
> Cpu(s): 9.5%us, 0.5%sy, 0.0%ni, 88.2%id, 1.7%wa, 0.0%hi, 0.0%si,
> 0.0%st
> Mem: 3631900k total, 3378056k used, 253844k free, 25488k buffers
> Swap: 4192956k total, 100k used, 4192856k free, 2356588k cached
>
> [postgres@server01 etc]$ free
> total used free shared buffers cached
> Mem: 3631900 3174804 457096 0 14280 2086184
> -/+ buffers/cache: 1074340 2557560
> Swap: 4192956 108 4192848
> [postgres@server01 etc]$
>
> Both commands show values ranging from 2GB to 2.3GB for the cached size and
> the server has 3.5GB RAM. I do usally see cached values with sizes bearing
> the size of the RAM in other servers. It seams that something is consuming
> the RAM and not letting it free to be used as cache for Linux files, right?
> The shared_buffers (256MB) is not high and I can not see a reason for this.
> Initially I've thought the problem was
> because the system was running with runlevel 5, but now, it's running with
> runlevel 3 and even so the values for
> cached size does not change.
>
> Any suggestions or directions I could follow to discover the reason?
what you have here I can take a guess.
--
Reimer
47-3457-0881 47-9183-0547 msn: carlosreimer@hotmail.com
skype: carlosreimer