Re: OT: linux kernel process krefilld

On 08/04/2004 09:56:35 PM, zhu chao wrote:
> Hi, Mladen:
> Using DirectI/O on linux/ext3/AS 2.1 with oracle 9.2.0.4? With
> filesystemio_options? Is ist supported by oracle? Can you give me
> some notes on this topic?

Yes, you can use Direct I/O on AS 2.1 with 9.2.0.4. There were 2 patches to 9.2.0.3 fixing some problems with direct I/O against ext3, but I believe that those were incorporated in 9.2.0.4 or 9.2.0.5 patchset. I'm afraid that Pete Sharman would be the right person to give the definitive answer. He always does. After all, he's a member of the birch table, isn't he?

> Thanks very much.
> I also changed the /proc/sys/vm/pagecache to
> [oracle_at_rac2 oracle]$ cat /proc/sys/vm/pagecache
> 2 5 10
> This seems to have some effect, as I see less kfilld running.
> [oracle_at_rac2 oracle]$ free
> total used free shared buffers cached
> Mem: 3347708 3072656 275052 0 239156 340784

                                                             ^
                                                             |
                                                     This means that you have
                                                     230M of file system buffers.
                                                     If I assume that oracle is the
                                                     only big thing running, then
                                                     it would mean that, in addition
                                                     to SGA, you are using 200M to
                                                     cache your data. If you let
                                                     the database run for a week, it
                                                     would be even more visible.





> -/+ buffers/cache:    2492716     854992

> Swap:      2048276     220856    1827420

Of course not! Linux box with 3GB RAM can take a lot of punishment before memory becomes scarce. Double buffering does add significant overhead, though and you really should consider using direct I/O. You can also use it against OCFS, which is quite easy to download and link. I'm not quite sure how would tar, ls and other utilities work against it, but I do intend to try it for the Labor Day.

-- 
Mladen Gogala
Oracle DBA
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