RE: log file sync and processes

Russell, Steve:

    From "YAPP Report Generator"
    "An option to reduce log file sync wait is to decrease processes parameter. The LGWR needs to scan
all processes to find each process that is waiting for the commit to be written."

    I really don't know if LGWR works that way or not. But it makes sense to me, when a process issues a commit, a commit marker is placed in the log buffer and that process signals LGWR process by taking the "redo writting latch" first, to be sure that no other processes has signaled it before...

    After that the LGWR has written all log buffer entries to disk, how does the process (or processes)
 that had issued a commit, know that their entries have been written to disk?

    I think that LGWR has to signal the process (or processes) that had issued that commit? am I right? Please let me know. Thanks.

Hope it helps.
Diego.

-----Mensaje original-----
De: Steve Adams <steve.adams_at_ixora.com.au> Para: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com> Fecha: Viernes 15 de Septiembre de 2000 5:34 PM Asunto: RE: log file sync and processes

>Hi Russell,
>
>The only negative effect of a high processes value that I am aware of is
that
>certain things that query the session specific data structures (such as
>autotrace) take longer. I am not aware of any impact on 'log file syncs'. I
>could believe that it might make them take longer, but short of timeouts I
doubt
>that it would cause more waits. If you try it, I'll be interested to know
>whether it has any effect.
>
>@ Regards,
>@ Steve Adams
>@ http://www.ixora.com.au/
>@ http://www.christianity.net.au/
>@
>@ Going to OpenWorld?
>@ Catch the Ixora performance tuning seminar too!
>@ See http://www.ixora.com.au/seminars/ for details.
>
>
>-----Original Message-----
>Sent: Saturday, 16 September 2000 1:31
>To: Multiple recipients of list ORACLE-L
>
>
>Hi,
> During a conversion we are getting very high numbers of log file sync.
We
>can't really do much with the striping and I am investigating some other
>options. One of the recommendations I have run across indicates if that
>this can occur if processes is unnecessarily high. In our case processes
is
>set to 1000 and the shadow processes are running around 90. I'm getting
>some push back from others who do not accept that a high number of
processes
>can have this effect. Anyone know of corroborating information from
experts
>or documentation? I don't see anything confirming it in Metalink or on
>Steve Adams' site.
>
>Regards,
>Russ Brooks
>
>--
>Author: Russell Brooks
> INET: russell.brooks_at_amctechnology.com
>
>Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
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>Author: Steve Adams
> INET: steve.adams_at_ixora.com.au
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Received on Mon Sep 18 2000 - 12:28:59 CDT