Re: postgresql + apache under heavy load - Mailing list pgsql-general

From scott.marlowe
Subject Re: postgresql + apache under heavy load
Date
Msg-id Pine.LNX.4.33.0401211644230.21832-100000@css120.ihs.com
Whole thread Raw
In response to Re: postgresql + apache under heavy load  (Alex Madon <alex.madon@bestlinuxjobs.com>)
Responses Re: postgresql + apache under heavy load  (Alvaro Herrera <alvherre@dcc.uchile.cl>)
List pgsql-general
On Wed, 21 Jan 2004, Alex Madon wrote:

> One can see that at the maximum feeling of swap (74700k free swap), the
> full picture is:
>
>
>  22:51:54  up  3:58,  6 users,  load average: 47.38, 18.53, 7.79
> 131 processes: 130 sleeping, 1 running, 0 zombie, 0 stopped
> CPU states:   5.3% user   3.0% system   0.0% nice   0.0% iowait  91.6% idle
> Mem:   384580k av,  210008k used,  174572k free,       0k shrd,    6372k
> buff
>                     158748k actv,   14556k in_d,    1412k in_c
> Swap:  265064k av,  190364k used,   74700k free                   31356k
> cached
>
>   PID USER     PRI  NI  SIZE  RSS SHARE STAT %CPU %MEM   TIME CPU COMMAND
>     7 root      16   0     0    0     0 SW    1.2  0.0   0:07   0
> kscand/Normal
>     5 root      15   0     0    0     0 SW    1.0  0.0   0:01   0 kswapd
>  7050 apache    15   0  8016 5896  1580 D     1.0  1.5   0:00   0 httpd
>  3870 madona    15   0  6540 1440   472 D     0.6  0.3   0:07   0 xterm
>  7032 apache    15   0  8336 7568  1980 S     0.6  1.9   0:00   0 httpd
>  7051 apache    15   0  4784 1640   280 D     0.6  0.4   0:00   0 httpd
>  2581 root      15   0 15928 1452   704 S     0.5  0.3   5:40   0 X
>  6985 madona    16   0   788  732   476 R     0.5  0.1   0:00   0 top
>  7023 apache    15   0  7956 7160  1736 S     0.4  1.8   0:00   0 httpd
>  7025 apache    15   0  7944 6816  1584 D     0.4  1.7   0:00   0 httpd
>  7027 apache    15   0  7808 6976  1588 D     0.4  1.8   0:00   0 httpd
>  7052 apache    15   0  6616 3584   404 D     0.3  0.9   0:00   0 httpd

this is really strange.  You've got 170Megs free memory, yet are going
into a swapstorm.  I had this problem with older kernels under rh7.2
(2.4.7 and 2.4.9) when accessing really large files but they went away
with the latest one I'm running, which is 2.4.20.

Are any of the underlying tables really large and maybe being seq scanned?
I'm strictly guessing here.  anyone else have any ideas?  I'm stumped.


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