Re: Performance Diagnosis

mccmx_at_hotmail.com (Matt) wrote in message news:<cfee5bcf.0406180648.298bc840_at_posting.google.com>...
> Anyone have any idea how to diagnose the cause of the 'rdbms ipc
> reply' wait event....
>
> A session will wait on this event when it waits for a background
> process to respond to a request. However is there any way to
> determine what background process..?
>
> This event accounts for a significant amount of the total response
> wait during the batch run (> 40%).
>
> AFAIK 'rdbms ipc message' is an idle event but 'rdbms ipc reply' is
> not.
>
> I've seen a note on Metalink which says that Truncating tables causes
> DBWR to flush blocks from the cache, and while this is happening the
> server process will wait on 'rdbms ipc reply'. We have a large buffer
> cache which could be a cause of a high wait time on this event.
>
> Are there any other causes of this event...

Would these waits be happening while you are checkpointing? Have you checked out DB_BLOCK_MAX_DIRTY_TARGET/FAST_START_IO_TARGET? http://download-west.oracle.com/docs/cd/A87860_01/doc/server.817/a76992/chx_inst.htm#434312 The general idea for your case is that you write out dirty buffers more often, which lowers the wait time because there are fewer to write at a given time. Of course, if you are generating many dirty buffers, this might not work.

Which version and platform, anyways?

jg

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