Re: Oracle memory allocation on Linux 2.6

From: Mladen Gogala <>
Date: 01 Apr 2008 16:28:26 GMT
Message-ID: <47f262aa$0$1342$>

On Tue, 01 Apr 2008 07:37:48 -0700, vitalisman wrote:

> With the latest Linux kernels, things have gotten hard to tune regarding
> the SGA/PGA we can allocate. I'm mainly talking about the physical
> memory that is allocated to the OS buffers/caches to make full use of
> the memory. With earlier kernels, we had vm.pagecache to control easily
> these amounts of memory. Now there is vm.swapiness with the unfathomable
> algorithm behind it (read: AFAIK we cannot really control the OS
> buffers/caches anymore.)

True. Linux is beginning to imitate Windows, even the shortcomings. No control over the VM that Unix OS was renowned for. Linux, too, started with undocumented algorithms and is taking control away from the system administrators. It is beginning to resemble an ego trip of yet another "IT industry giant", namely Ken Olsen. To make long story short - Linux sucks. I am awaiting a competing OS. What they did with 2.6 is a disaster. Competitor is bound to appear, sooner or later. My money is on some flavor of BSD. This is not the first time things like that have been discussed here. As far as I can recollect, Noons was also very critical of Linux, same as Kevin Closson.

> Moreover, SGA locking is not possible (or rather not advised by Oracle
> support) and it is really difficult to check how much physical memory
> our SGA is actually using. Even with vm.swapiness=0, huge amounts of OS
> buffers/caches get

Do you have FILSYSTEMIO_OPTIONS set to either "SETALL" or "DIRECTIO"? In my experience, that will significantly reduce the use of caches.

Received on Tue Apr 01 2008 - 11:28:26 CDT

Original text of this message