Subj : Re: linux memory
To   : comp.os.linux
From : Hacker Beware
Date : Fri Aug 06 2004 12:31 am

"utkanbir" <hopehope_123@yahoo.com> wrote in message
news:f6c90ebe.0407282246.27bdf7ad@posting.google.com...
> Hi
>
> This is related to linux / oracle , i have asked this question to
> oracle support also .
>
> My box is hp , redhat linux advanced server 2.4.18-e.37smp , 4 itanium
> 64 cpus , 8gb.ram and oracle 9.2.0.5 with rac (2 nodes) . I use ocfs ,
> this is a tb.level datawarehouse . My question is related to memory
> usage of linux.
> Although i have 8gb. of ram , oracle shared memory is about
> 1.6gb.(ipcs) . My swap size is 24gb. When i check the system by using
> top , etc.... , i see most of the memory is used , and a great amount
> of memory is used by linux for disk cache. This is the /proc/meminfo
> output:
> total: used: free: shared: buffers: cached:
> Mem: 8490827776 6121046016 2369781760 0 29163520 1254342656
> Swap: 25165725696 1141850112 24023875584
> MemTotal: 8291824 kB
> MemFree: 2314240 kB
> MemShared: 0 kB
> Buffers: 28480 kB
> Cached: 1040144 kB
> SwapCached: 184800 kB
> Active: 3157680 kB
> Inact_dirty: 401984 kB
> Inact_clean: 16656 kB
> Inact_target: 715264 kB
> HighTotal: 0 kB
> HighFree: 0 kB
> LowTotal: 8291824 kB
> LowFree: 2314240 kB
> SwapTotal: 24575904 kB
> SwapFree: 23460816 kB
> Committed_AS: 16057008 kB
> HugePages_Total: 0
> HugePages_Free: 0
> Hugepagesize: 262144 kB
>
>
> Look at the cached value , here it is about 1gb, , this number reaches
> up to 6gb. I read some articles about linux memory management ,which
> says such a thing is expected behaviour for linux (if there is memory
> use it instead of waste) . But the value increase too much that the
> machine starts paging. (look at the swap values above) And most
> importantly , i use ocfs which uses direct io , so do i get any
> benefit of this linux disk cache? (since direct io does not use any os
> buffer ) Why does linux incrase the cache size too much and than
> starts paging? Whats the benefit of swapping ?  Why does not linux
> prevents allocation of cache memory and stop swapping?
>
>  Kind Regards,
> tolga



If you have that type of box, I am sure you paid for RedHat.  I would call
them for support on the system.

There are probably a few dozen people in the world with access to that type
of ram and cpu's...

.