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...
>
> Matt

From Steve Adams's ixora site:

rdbms ipc reply waits indicate the either DBWn's write batch is too big, or you are checkpointing too intensively. Make sure that db_files is not much higher than the number of datafiles that you actually have. If you are using incremental checkpoints ( db_block_max_dirty_target) don't be too ambitious. Received on Fri Jun 18 2004 - 13:25:21 CDT