Re: buffer busy waits and v$filestat

That's On 2003.07.29 19:59, Diego Cutrone wrote:

> Another thing I think (I'm sorry to disagree with
> Mladen on this) is that when DBWR hasn't finished
> writing a buffer to the disk, and a session wants that
> buffer in exclusive mode, there's a wait and that wait
> is computed as a write complete wait and not as BBW.

DBWR works in 2 phases:
a) It scans for dirty buffers and pins them. b) It starts IO, usually using writev.

If IO has been launched and not yet finished, then the wait is "write complete wait". If IO hasn't been started yet, we have "buffer busy". This "write complete" wait became essential with the advent of asynchronous I/O. I was just simplifying things, nothing else.

-- 
Mladen Gogala
Oracle DBA
-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Mladen Gogala
  INET: mgogala_at_adelphia.net

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